One of the best things I can report about being a grownup is that, as it turns out (and as I always suspected), my high school PE teachers were often wrong. Exhibit A: It didn't end up ever mattering that I couldn't hit a baseball to save my life -- and thank goodness for that. And, Exhibit B: It is not always true that quitting makes you a loser. Much has been made lately of fantastic failures, of the redemptive possibilities of going down in flames.
Here's a revolutionary idea for you: When you get the feeling that you're ill-suited for a job, or a place, or a friendship, or a fashion trend, do yourself a favor—quit. There are no prizes for slogging through something that makes you miserable. Unless you're in high school PE—that, you just need to suffer through until it's over. Sorry about that.