+1 to what Jay said.

If you're just a hobbyist, then it shouldn't matter. Work when the mood strikes and consider it a hobby like anything else (watching tv, playing games, etc). If you're serious about it as a career and you have to consistently force yourself, then maybe you're more in love with the "idea" of being a CG artist, rather than actually being one. Advice? Turn off the idiot box and gaming console. Find some challenging projects to work on. Set a goal. Set a deadline. Look at some of the higher end modelers out there and strive for that kind of detail. Practice modeling something out of your comfort zone. Learn other CG areas aside from modeling. You could spend a lifetime learning this stuff.