I do this, and have been for the better part of a decade. I regularly hike, lift, do yoga, meditate, eat well, journal, don't drink, am in a decent work/financial situation, have a loving family and girlfriend, good friends, get in bed at a reasonable hour, and have done years of CBT therapy. I'm in better shape than 90-95% of people I see. Depression symptoms have hardly changed. Still have suicidal ideation, frequently intense headaches, anhedonia, fatigue, insomnia. Lifestyle has helped with self-control and caring less about the symptoms, but little has changed with their frequency/intensity. I'm pretty stable, but my quality of life is by no means exceptional.

I really doubt I'm a rare case, too, but maybe that's not true. I have a lot of faith in therapy, as it helped me, but experience has shown me that lifestyle and therapy alone won't drastically alter the actual presence of symptoms. Also briefly tried a few different prescription drugs years back without them yielding any worthwhile net benefit either.

All this said, my issue and many other people's issue with the referenced meme and similar common attitudes has nothing to do with the fact that healthy habits lead to a better experience of life. Of course that's the case, and all people with mental illness should do so. We mostly all know that and live varying degrees of healthy lifestyles, though, by necessity.

The issue has to do with the highly misleading notion that if someone leads a healthy life, they will no longer have symptoms of mental illness, or will have few symptoms. This simply doesn't have a basis in reality for many of us who have already made every lifestyle change suggested, so the advice comes across as fairly useless and patronizing advice from people who have very limited experience with the actual illness. Thus, at some point it has to be accepted, by the sufferer and by people who actually want to relate in a human way to people with these illnesses, that having present symptoms does not mean someone is a weak or unhealthy person, as is the false perspective which is very commonly propagated.