Check out the #100DaysOfX Challenges Project. Changing your habits you are changing your life. Remember that the best time to start is always NOW.
I recommend that you commit to no more than 2-3 challenges at a time, ideally 2. If you are doing the #100DaysOfCode which involves a lot of mental activity, try the #100DaysOfHealth, or #100DaysOfFitness challenges. There is so much more on the site, check all of them out and choose the ones you want to acquire! Languages, writing, meditation, journaling, cooking, and more!