how much do you work out and how hard is it for you to stick to your regimen?
Maybe 30-40 minutes 4 times a week, but I've only been doing that for about the past 4 months, if that. For a long time, I was too ill to work out and I lost a lot of weight and fitness which I'm now regaining. Since I started working out again, I've gained 11kg of muscle, though I haven't managed to make any gains for about a few weeks now, and am now at 81kg; as heavy as I've ever been.
It's not really that hard to stick to, provided I have the energy for it and can keep myself from being distracted. The hardest bit is starting again after having to stop to recover for a few days, since sometimes it takes a while to heal from a particularly intense session or one that exercises new muscles. It was a little easier when I was at school, since then I'd do it at lunchtime each day, but I've got somewhat of a routine going at the moment too.