Took sertraline for over year, also tried bupropion, paroxetine, aripiprazole, and others.
Sertraline made me feel a bit "numb" overall. Negative things didn't hit me as bad, but positive things also didn't move me as much either. Lithium and aripiprazole given similar effects, but at a much greater magnitude, and much greater side effects (extreme nausea for me). Combined with Cognitive Behavioral Therapy, I think the idea is to have sertraline reduce your latent stress response and to have your doctor / CBT help you establish rational control. Then take out the drugs like you'd take off the training wheels. Though some people stay on sertraline for a long time (perhaps too long?).
Sertraline definitely changes your personality on a global level, but the total magnitude of the change appears slight (at least to me). Overall it made me just more blithe in the steady state, for better and for worse. Except during the 2-4 weeks following a dosage ramp-up. Then I actually got increase stress-- dangers felt larger-than-life, and I lost confidence in being able to overcome some physical dangers. It was like the signal-to-noise of the stress response was off. After the 4 weeks, though, that surreality went away.
The most objective change for me was in terms of exercise-- all metrics of performance went down at least 10-20%. Dosage increases made me feel like I was recovering from an injury-- my whole cardio felt off.
Where sertraline made me feel less productive, bupropion made me feel better, even "good" or "winning" at times. Bupropion gave me little 'micro seizures' at times, though, and my sleep got worse, as if I was taking a ton of caffeine.
I think the common notion that anti-depressants magically make you feel better is wrong. Bupropion is close to that notion-- it's technically a bit of an upper. But sertraline is just kind of a nullifier.
After the experience, it's clear to me why some of my colleagues in Silicon Valley (even my roommate, now at FANG) take cocaine or adderall. If all you want is the "win" feeling and don't care about the consequences (or think you're bigger than them), uppers make a lot of sense. Sertraline is more for dealing with extreme sadness or threats, like the fear of failure or of violent colleagues.