besides therapy and medication, other things you can try are: exercise for 30 minutes (releases endorphins), eating healthy foods (no crash afterwards), sleeping well (to have your mind at 100%), look into getting a seasonal depression light (if you live in part of the globe with overcast skies in the winter).
try exercise, you could either go for a walk/run - or stay inside and look up home body weight exercise. You could also choose to look up a yoga video on youtube. The endorphins from the exercise will help you feel better