I agree with the enjoyment aspect, but I think it’s even more than that. I think it’s a real love for your instrument & the playing of it. Like everyone I don’t have a lot of free time, & I want to make what little time I have really count, but it’s not always like that.
All the dedication & disci[line can’t help on those days when you’re just off & nothing seems to be working out right, but it’s the love of it that keeps you going. Like my teacher says, music & fun & frustrating all at the same time.
I say play when you can, even when it’s not a good day, it is, because you’re there & you’re doing it & you’re learning from that experience. If you try to force the discipline aspect it may make you feel like it’s more of a chore, & then you may shy away from it.