A significant amount of the artist population is depressed or has experienced it at some point. The same could probably be said about the population at large.
Depression is caused by a variety of criteria.
For me, it is the space between where I am and where I should be or what I'm capable of. This is also known as the point of suffering. This suffering can be so intense at times that I turn to substance. For me, those substances are booze and cigarettes. The alcohol blocks out the noise and the cigarette provides me the reward.
Yes, cigarettes are bad, but they do address the reward center in your brain. If you are not getting rewards in every other area of your life, the cigarette provides that instant reward that allows you to keep moving.
Everyday is different. Exercising can help to level you out, but it can also be a trigger.
Right now, I feel fatigued because I am hungover from the day before last. Although this is how I feel, I am going to stay committed to the process because that helps improve the overall outcome I'm looking to achieve, which reduces overall suffering.
You need to be able to push through these valleys. The next days can change for the better and when they come, you will appreciate the grit you displayed.