What it all boils down to with depression. Is your thoughts.
Control your thoughts and you control your life.
Meditation in particular mindfulness helps as does the gym etc.
But the problem with most of us is that we are too busy working and dealing with life at 100 miles an hour that we don't have any time to spend on us.
I haven't been to the gym for a long time, by the time I get home I just don't have the energy. I don't eat healthy because I don't have time to cook. I don't have time for hobbies because all weekend is taken up with doing what the family wants to do. I don't have time to meditate, go get a massage etc.
The list goes on we just put out heads down and plough through life feeling like a bag of poope.
They call it the rat race, and it's true we are just racing towards our graves without taking time to reflect and really enjoy life. Its all about money, which is a pointless pursuit in itself... No wonder we are all depressed.