Here is the deal. You are not borne diligent. So you must work to cultivate the habit. That means, you must work against your instinct nature, because you are naturally lazy. Once you have the doubt, think about jogging: yes, it is painful to do it, but it is even more painful to regret. Given the two evils, pick the lesser.
The main reason of depression is the loss of hope, not just the on-going reality. To get out depression, you must act, no matter how discomfort it is. The tolerance of discomfort is one quality you must develop.
Keep that in mind.