Honestly, I believe everything happens for a reason. I have regrets, but looking back at some of them, it was for the best that I didn't take advantage of some of them. I sorta regret being a bit of a coward when it came to girls during middle school, as pretty much anytime I was interested in a girl the feeling was almost always mutual, but I was too scared to just ask them out. Looking back, I wasn't exactly the cleanest guy (lot of stuff going on at home that contributed to that) and if I had gone out with some of those girls I imagine the would have told stories and spread rumors and damaged my reputation, such as it is.
If there is any one thing I regret, its not figuring out what I truly want to do with my life career wise until 5 years ago or so. When I initially graduated from high school in 98, I chose Comp Science as my major, and it was a complete disaster. I had very little interest in it and my grades showed it. 5 years ago I went to Gibbs College for Graphic Design, and fucking loved it. In a way, my career path was blaringly obvious; I had numerous teachers in HS and even friends who were genuinely shocked I wouldn't pursue art further and just never understood why.