Why is it like this? I think it’s because if musicians stop practicing, you notice more quickly. If I went to an orchestra rehearsal after a week of not practicing, my fingers would feel sluggish and my lips would hurt. Practicing as a musician is possibly as much about retaining your current skill as it is about improving. But in programming, your skills don’t regress so quickly: practicing is more about just improving your skills. So when we don’t practice, we don’t feel an immediate, negative reward. We just miss out on the better skills we could’ve had.
Source: Programmers and Musicians