...what you get out of it depends on what you put into it - and why. If performing at a certain level for yourself or others is the goal - whether professionally or as a hobby - then practice on some sort of formal level is probably inevitable: scales; exercises; sight-reading or learning charts; ear training; what-have-you.

But..there is a rather unorthodox approach to a relationship with a musical instrument that focuses more on intimacy and is less dependent on results. It incorporates other senses that produce feelings of satisfaction that go beyond (or sidestep, if you are rationalizing) accomplishment.

You take pleasure in the feel of the wood, for example, or you like the way it smells. Maybe you are curious about how a certain passage heard on a recording is played, and so you focus on just that part of the song, and forget about the rest.

This is probably a very egocentric approach to take, but it can give just as much satisfaction as applause from a crowd, because you are doing it for yourself and you are the only judge of how well you meet your own expectations. You don't bend to another's demands upon you, and you don't need someone else's approval in the form of fame and fortune as a measure of your own musical worth.   

Which is probably good, because by all accepted standards you probably won't be worth a tinker's damn, but you don't care. You are content with becoming instead of being. Everything is a work in progress, and completing a process and calling it done feels sort of like going to a funeral.