Now that I've practised anatomy - which was hard and sometimes boring for me - I've come to think that practising drawing really rewards itself. First of all; you learn to draw quicker and the pictures don't take so long time to make -> unless you want to focus on details and make everything perfect. When you're quicker you probably have the energy to focus on them. I haven't reached that stage just yet..
Secondly, you can always surprise someone with your new talents. I rarely draw anything I would show to my parents but people see the change on the internet too. By the way: I can't highlight enough how important critic is to me. Some people think it's rude but I want people to tell me what is wrong especially if I don't see it myself. Because one can always practise their mistakes.
Third reason is that you start to view the world differently in a good way. My example is the colours: I can easily recognize all the tones from each other and tell which colour is warm and what is not etc. This sounds easy but I realized my talent when we practised colours in our school. People had told before I have a good colour-eye but that one proved it. It's a good thing to have because I'm thinking of doing visual marketing in the future.
At some point when drawing is easy enough, you start liking it from the bottom of your heart. Example: When you're sketching on school while (hopefully) listening to you teacher, you don't even think what you're drawing, you just draw. This is the fourth reason.
Last but not least: Reason five -> You become proud of your own work. Artist is his own worst critic after all. I'm not exactly sure what happens in this because this is way ahead of me. Not sure if you can truly achieve this neither because there always seems to be something to improve or some ways to make it better.