I started working out right before high school. My first year of high school I wrestled and was extremely lean. The rest of high school I rowed competitively and was captain of the team. I gained some weight while rowing, but the amount of calories I was burning made it incredibly difficult to gain weight. Once college came around I started lifting weights more often and for longer periods of time. This added some muscle, but I never really had a specific routine. I just made sure to work out all of my muscles. Towards the end of college I came into contact with a professor that used to judge bodybuilding competitions and even wrote a book about bodybuilding. Using his principles I have gained weight at a faster rate. Can't say it's easy though. I'll probably be changing my routine here soon.
I feel better about myself and that I've accomplished something every time I end my workout. Not to mention I feel happy in general after working out. It keeps my body healthy and gives me something to do when I'm bored and is a good way to blow off some steam. Bodybuilding is also something I can constantly build on. I can add goals and there's always something I can can try and improve. Bodybuilding is important and I always anticipate working out and feel awesome (sometimes) once I leave the gym.