I think that what works is different for everybody, and in my own experience, can be different for the same person at a given time in his or her life. As Kestra
said, self-treatment, like with exercise, medication, and therapy are all good options to look into. I have bipolar 1 disorder. For me personally I have found both medication and cognitive behavioral techniques (I say techniques because I've never had therapy, but rather use techniques I've learned from my own education in psychology) have both worked well. While I credit medication for saving my life (bringing me down from a major manic episode and also bringing me up from a major and suicidal depression), I did find that for day-to-day living medication was too much for me, and I can manage my bipolar well with daily exercise and other behavioral techniques.