Bipolar is a physical illness. I believe moderate to major depression is too. I do not believe you can cure them just by changing your thoughts any easier than you can cure cancer by changing your thoughts, although you do hear about rare cases where that happens. But that's rare, and usually a physical intervention is needed. For bipolar and depression, I believe the best physical intervention is a micronutrient approach like Empowerplus.
However, I do believe it was poor thought choices that made me sick in the first place. It would be easy to blame it all on my thyroid, because bipolar is a symptom of Hashimoto's. I probably had my first hypomania when I was 10, that I remember, and my first depression when I was 11. Long before puberty. I don't know if the Hashimoto's would have already been active then. You do read about infants and toddlers with hypothyroidism, so it may be possible.
I do recall that at an early age, 8 or 9, I became attracted to the idea of being "jaded." I liked that "been there, done that, bored with it all" aura that some people had. It struck me as a way to be interesting, and I wanted to be like that. Gradually I stopped taking pleasure in things.
A movie score would have a dramatic minor chord there. I really think now that was the beginning of it all. Probably the hallmark of my long adult depression was a complete inability to appreciate anything. I was living in the beautiful San Francisco Bay area, with the sunshine and the sea air and flowers all year long. I knew someone else who had recovered from depression, who told me that he loved just going for walks and seeing all the flowers. I went for walks and looked at the flowers and I felt nothing. I looked at them and knew intellectually that they were beautiful, but they did not make me happy.
Daily exercise, by the way, in the sunshine and sea air, also did nothing to improve my mood.
So, I had periodic depressions in high school and university, and very productive periods that made me successful in school and work. The two years leading up to my breakdown at 35 were progressively more and more stressful. I had a fairly heavy travel schedule that kept me physically off balance, and an increasingly more adversarial work environment. Looking back, I see that a lot of that was my own fault. I saw slights where none was intended, and I consistently looked at the negative side of the situation. You may not be able to control the situation, but you can control your reaction to it. I always saw things in the worst possible light.
When you are feeling bad it is your spirit sending you clues that things are not right. If you ignore the clues they get bigger. It took many years of seeing things in a negative light, and ignoring my feelings and physical symptoms, for things to collapse totally. I do believe that my brain has always worked a little differently, which is why I was hit with bipolar depression instead of heart disease or cancer, but it was my own thoughts that created my physical illness.
That is why I think Cognitive Behavioural Therapy (CBT) and meditation are such an important part of recovery. Physical help such as Empowerplus will only get you so far if you have a negative thought pattern, which I believe is the root cause of illness. Learning to feel our feelings, and accept the guidance that they are giving us, is crucial to long term success.