Before you start influencing hordes of TRP'ers, most of whom have a glaring lack of understanding of science and human physiology, to go to their nearest Vitamin Shoppe to buy 5-HTP pills, please realize that taking 5-HTP pills has time and time again been shown to do virtually nothing for mood improvement. In fact, in some people, taking 5-HTP can worsen depression and the emotional lability associated with bipolar disorder and things like early dysthymia. Here's a good summary article about the topic.
Brain physiology, especially serotonin biochemistry, is nowhere near as simple as you try to make it out in your post.
I read your post and I see people below talking about eating pumpkin seeds to make them happy...that's not how the body works. Tomatoes have HUGE amounts of serotonin in them, but you don't get a rush of good feelings when you eat tomatoes because serotonin (5-HT) and its precursor 5-hydroxytryptophan (5-HTP) have a very difficult time crossing the blood-brain barrier. They can cross it in certain doses and if certain drugs are added, but by themselves they have enormous difficulty. So if you take lots of 5-HTP it will build up in your bloodstream, but very little will get into your brain and effect a change.
Thank you for mentioning to never take loads of 5-HTP before taking "molly" (MDMA). This can cause a deadly effect called serotonin syndrome which can kill people.
You make it seem like understanding neurotransmitters makes you understand people way better – that's ridiculous. Knowing the effects of the neurotransmitters is only a piece of the puzzle, and you neglect to mention how much interplay there is between the various neurotransmitters. Serotonin alone has 10+ well known receptor subtypes, all of which have different functions. Like you said, we still barely understand why many hallucinogens specifically target serotonin pathways. You cannot make an accurate prediction of your serotonin levels based on your mood and current feelings, and you definitely cannot make an accurate prediction on others based on what you think their serotoninergic drive to be at that current time.
I appreciate your attempt to persuade people to listen more to their bodies (meditate) and try to see how their mood and feelings change. This is a great step for all people and something I would definitely recommend to TRP'ers. However, again, all you keep doing is things we see serotonin play a role in. You neglect to impress how much interplay there is between neurotransmitters and that they don't work alone and their functions are not so clear cut.
To all the TRP'ers that are about to downvote, please remember two things. One, I've been a TRP'er for almost 3 years, so I don't mean "TRP'er" to be derogatory or sarcastic. Two, and more offensively, a lot of you have a very poor understanding of science and scientific research. Obviously, just like "AWALT" doesn't literally mean "every single woman," I'm not referring to those of you in the hard sciences or those of you (e.g. many of the mods) who are actually well-versed in the scientific method. But a lot of you seem to think that one or two papers showing some evidence of a phenomenon proves a phenomenon. In reality, it does not.