I learned to accept that I feel bad sometimes and it made me happier.

But I went farther than that.

I also learned to accept that my ideas and behaviors are inconsistent and it helped me better understand the world and myself.

And finally, I learned to accept that I sometimes do bad things (and desire to do even more bad things) and it made me a better person.

(Disclaimer: my experiments have n=1, no control group and subjective measurements chosen in hindsight.)