From what I've heard and understand, gender dysphoria preludes transitioning. After all, if you don't have gender dysphoria, why would you go through with transitioning?

This is a subject of some debate within the trans community itself, so I do not speak for everyone. But what I would say is that not being terribly distressed does not mean you wouldn't prefer things a different way - you don't have to hate one job to prefer another, for instance.

Why people may feel contentment after transitioning may be due to placebo effect or perhaps due to telling themselves this is how they were meant to be and believing it after a long time.

You have no evidence whatsoever to support that conclusion. There is, however, a tremendous amount of information to support the notion that transitioning is beneficial:

• Heylans et al., 2014: "A difference in SCL-90 [a test of distress, anxiety, and hostility] overall psychoneurotic distress was observed at the different points of assessments (P = 0.003), with the most prominent decrease occurring after the initiation of hormone therapy (P < 0.001)...Furthermore, the SCL-90 scores resembled those of a general population after hormone therapy was initiated."

• Dhejne, et al. is much-cited by those who like to say that we have elevated mortality post-transition, and it does in fact say this...for the cohort who transitioned before 1989, in a far more hostile world and with less effective treatments. However, there was not a significant elevation of suicide or of other mortality in the post-1989 cohort.

• Colizzi et al., 2013: "At enrollment, transsexuals reported elevated CAR ['cortisol awakening response', a physiological measure of stress]; their values were out of normal. They expressed higher perceived stress and more attachment insecurity, with respect to normative sample data. When treated with hormone therapy [at followup, 1 year after beginning HRT], transsexuals reported significantly lower CAR (P < 0.001), falling within the normal range for cortisol levels. Treated transsexuals showed also lower perceived stress (P < 0.001), with levels similar to normative samples."

• Gomez-Gil et al., 2012: "SADS, HAD-A, and HAD-Depression (HAD-D) mean scores [these are tests of depression and anxiety] were significantly higher among patients who had not begun cross-sex hormonal treatment compared with patients in hormonal treatment (F=4.362, p=.038; F=14.589, p=.001; F=9.523, p=.002 respectively). Similarly, current symptoms of anxiety and depression were present in a significantly higher percentage of untreated patients than in treated patients (61% vs. 33% and 31% vs. 8% respectively)."

• Here is a broad survey conducted in the UK. Unlike the previous links, it's not peer-reviewed, but the large sample size provides some corroboration of the above results. In particular, we have: (Page 15): "Stage of transition had a substantial impact upon life satisfaction within the sample. 70% of the participants stated that they were more satisfied with their lives since transition, compared to 2% who were less satisfied (N=671)" (Page 50): " Most participants who had transitioned felt that their mental health was better after doing so (74%), compared to only 5% who felt it was worse (N=353)." (Page 55): "For participants who had transitioned, this had led to changes in their self-harming. 63% felt that they harmed themselves more before they transitioned, with only 3% harming themselves more after transition (N=206)." (Page 59): "Suicidal ideation and actual attempts reduced after transition, with 63% thinking about or attempting suicide more before they transitioned and only 3% thinking about or attempting suicide more post-transition. 7% found that this increased during transition, which has implications for the support provided to those undergoing these processes (N=316)."

• de Vries, et al., 2014 studied 55 trans teens from the onset of treatment in their early teenage years through a follow-up an average of 7 years later. They found no negative outcomes, no regrets, and in fact their group was slightly mentally healthier than controls.

• Lawrence, 2003 surveyed post-op trans folk: "Participants reported overwhelmingly that they were happy with their SRS results and that SRS had greatly improved the quality of their lives. None reported outright regret and only a few expressed even occasional regret."

• Michael, et al. 2002 found a suicide rate of roughly 1% among post-op trans people, which is aligned with the general public (and greatly reduced from the double-digit values typical of untreated trans people)

but from where I am, I do not see transitioning as good or healthy

You can argue morality if you like (I won't), but it clearly and overwhelmingly improves the health of trans folk. And if my word, the word of hundreds of others who have experienced it, and dozens of studies on the subject aren't sufficient to convince you, that's also the official position of the APA. If you want to argue that reduced suicide, depression, and anxiety rates and overwhelming satisfaction are bad, go ahead, but you cannot argue the fact that those are the results of transitioning.

If it (your sex) was not causing you problems, why would you want to pump yourself full of artificial hormones?

It was causing me problems. That's the entire point. I was depressed and anxious most of my life, and it was so background to me I was only dimly aware it was possible to be otherwise. The day I realized this was something I could do was, without exaggeration, the best day of my life. Overnight, the grass was green, the birds were singing, and I could have what I'd barely even dared to dream of.

The body is meant to be respected and cared for, not mutilated chemically or physically.

We alter the body in many ways when it causes us distress. You would never, for instance, tell someone with chronic pain not to get surgery to relieve it. Transition is essentially the same thing: a modification to the body to relieve distress.

The problem rests in the mind.

Then why do mental treatments not work? Attempts at conversion 'therapy' and the use of typical psychiatric medications have failed to improve dysphoria at all. Modifying the body, however, virtually always relieves dysphoria to some extent and may cure it completely.

Why did you feel the need to transition in the first place?

This is a question with a lot of levels. The simplest answer is "I don't know for certain, but I did". The scientific answer appears, as best it's currently understood, to be related to hormonal exposure during very early fetal development. The answer, insofar as I chose to actually transition, is "because it made me giddy to think of doing it, every step I took towards it made me happy, and I had no good alternate explanation for my feelings".

Was it brought on by contemplating the lifestyle of the opposite sex and liking it?

My lifestyle has changed little as a direct result of my transition. I dress differently, and I guess I'm a lot more physically affectionate, but that's about it. All the other differences are the result of being much happier and much more confident with my body today.

Or was it something darker like a parent trying to force you to be what you were not?

Does it not strike you as just slightly presumptuous to assume that the only reason someone could take a track in life you disapprove of is that they were abused? No, I was not abused, and in fact I grew up in a very conservative family with quite traditional notions of gender.

Perhaps it was brought on by telling yourself life would be better as the other sex.

My life is better as the other sex.

Regardless of the reason, your body is important

Yes, it is, and that's why it's such a relief to finally feel like it's my body, a body in which I can fit and be comfortable.

To twist and distort what your body is by any means nessassary, is intrinsically wrong/evil.

I simply cannot agree that relieving pain and bringing joy is wrong.