Do you choose how you feel?
I mean if your depressed do you choose to be depressed if your happy do you choose to be happy?
depression and happiness has a lot to do with homornes. Depressed people have an inbalance in certain hormones that is usually due to genetics. Hapiness can be due to hormones as well, like when one eats chocolate they usually feel better, if you do something nice for someone or someone compliments you, studies show theres an elevated level of serotonin in these people which gives you that feel-good happy feeling. It could also be a body response. For example if you smile a lot, you tend to feel more happy because thats how your body responds to a happy emotion...its pretty complicated!
No you cant choose how you feel.
You can choose how you look at things, or how you deal with things, but you cant really choose how you feel.
You cant really compare depression to happiness - one is an illness while one is an emotion/mood state. People who are depressed dont choose to be depressed. It is an illness with a very real biological cause.