Biggest struggle: caring too much about what my parents think about my life decisions. They are wonderful people whom I love, but extremely controlling and with a very narrow idea of what defines success. Sadly I have little in common with them and spent years trying to please them and make them proud only to figure out 1) what I want out of life and what brings me happiness are not things they care about and 2) I was passing up great potential career opportunities that I was passionate about, but that they seemed to think were stupid. Follow your dreams and don't let everyone else influence your decisions even when it's your own family! They might have their vision for what they want you to be, but you're the one who has to live with what you become.
Biggest failure: Finding the gal of my dreams and doing the stupid beta male thing where I freaked out because I realized that she really loved me and at the time I was way too selfish and immature and insecure to know how to handle it (I think inside I really believed she was too good for me). I didn't think I was truly ready to commit to her, so rather than breaking it off in a mature way and at least staying friends, I was a complete d*ck to her. I won't elaborate on what all I did, but it totally broke her heart, which I guess achieved my desired outcome at the time of "setting me free" but she never spoke to me again and I regret it terribly. That was a few years ago. To be honest I never would've guessed she would have cut me off so thoroughly, I figured I'd always have a second chance with her. But now I am going down a dark and sad rabbit hole.
Don't do what I did, kids.