Gymnastics when I was 10. I enjoyed leveraging my own body weight in the sport and had a pretty strong upper body from the start. I went to my first weight training camp when I was 12 and was hooked on free weights. Bench press became my favorite lift. I just had a small weight bench in my parents fitness room with some free weights, so my options for exercises were somewhat limited. When I was about 15, I started incorporating more compound movements such as power cleans and dead lift into my regime. I had no idea how strong my back was when I first started doing DL and I actually pulled 345 in my first max attempt. I got hooked on dead lift and that became my new favorite exercise. I continued to lift heavy all through college - I found it to be a great way to relieve stress and refocus my mind before and after tests.
I've always enjoyed watching World's Strongest Man on TV and it's always been a dream of mine to compete in the sport, but I never thought I would be able to push myself to that level for an extreme sport like Strongman. But all of that changed my senior year in college: I was cruising around on the web and noticed that there was a local strongman contest in the area and I had about 3 weeks to prep for it. I had such a blast at the contest and was hooked after that.
Most of my training is now concentrated around strength building. Size and definition is something that inevitably comes with lifting heavy weights.