Based on my own past experiences, here are some of my suggestions for getting creative juices flowing.
I. One-Month Challenge

When I wanted to draw more, I bought a small sketchbook and wrote on the front cover my goal to spend at least 15 minutes a day doing some art in the book for 3 months. My main focus was using different media and relying on my imagination instead of just drawing what I see.
The result of my drawing challenge was wonderful and captured a lot of creativity and expression over the days that passed. By the end of the 3rd month, it felt like a bit much and thus I recommend doing it for either 1 or 2 months. You could do this for a variety of hobbies you’d like to get back into, such as with writing, knitting, or another craft. (I uploaded some of those entries in my “Random Life” page.)
II. NaNoWriMo

For any writers out there, I’d like to let you know about the NaNoWriMo (National Novel Writing Month) challenge to write a novel in the month of November. Your target number of words and length of time can be adjusted if you don’t want to feel so rushed (I did half a novel over November & December), but if you sign up on the website you can see others in the community who are also working their way through writer’s block, as well as see a chart of your own writing progress over time. Even if you don’t make your goal, it still can get you writing more than you were before and I’d call that a victory!
III. Starting Small

Staying engaged with something overtime can be really important, as anyone whose struggled through a long book knows. But even if you only read a few pages a night, you will eventually reach your goal. Developing a habit in the gym, music, or art could benefit from fighting through in the beginning and instead of dedicating a lot of time on one day, doing 15 minutes per daily. (This is actually advice I’d heard while learning to play the violin.) This could help you from burning out, and if you feel a bit bored with the music, etc., try some new genre or project with it.