Was once a sponsored triathlete, competed in every distance from Sprint to Ironman (Rev3 Cedar Point, finishing photo is on here somewhere). I always found myself hitting the gym aggressively in the winter, bulked up, and lost it all just as it warmed up enough to train outside again... Until I finally saw the light and began strictly focusing on diet, strength training, and some cardio(just much less than before!). No looking back.
Bodybuilding, to me, is a lifestyle that I enjoy. I enjoy cooking all of my meals, buying all my own groceries, planning for future meals, getting my macronutrients, and doing this daily and consistantly. Obviously I love the gym aspect of it, but it's so much more. Your clothes fit better... you feel better... people ask you for fitness advice... and it honestly there's a huge fun and challenging aspect to it. You set your goals, you fight for them, and once you achieve them; you're addicted.