I'm a guitarist in 2 heavy metal bands and an industrial designer. For the first few years of working full time as a designer I lost my creative drive as a musician. I got it into my head that my creativity was a finite resource that I was using up at work and therefore there was nothing left for music.
What I have realised over the past year or two is that this was an excuse that I had given myself to slack off. Yes, design is important to me and it's how I make my money (and for that I am very fortunate), but music is also important. Playing music is a different kind of creativity and makes me feel great.
My advice would be to only give your time to people and activities that deserve it. Don't waste time, and try to limit TV watching. My girlfriend is the community manager for a major international review site and she is always going out and doing events so I dedicate the time she's away to music.