We need rewards to be happy and feel good about ourselves. When we work really hard for no reward we get depressed and discouraged. Maybe you're working really hard at a job and they won't promote you or give you a raise. Maybe you're working really hard on a business but there is no demand for what you're selling. Maybe you're working really hard on a relationship and the other person isn't reciprocating.
Are you doing something rewarding? Rewards can come from work, hobbies, exercise, etc. They can come in the form of money, being in tune with your values, helping others, improving yourself, etc. If you're spending a lot of your time and energy doing something that isn't rewarding enough, perhaps you want to try something new.
Hope you're dong well.
You can learn more about depression and how to heal yourself at www.depressiondodging.com