Becoming the best you that you can be, should be a very attractive proposition. When you accomplish something of magnitude that gives you a sense of pride, are you feeling better or worse about yourself? If you read a personal development book that gives you a tidbit of information that improves your life, do you walk away feeling better or worse? After ingesting a recording designed to uplift your outlook on life, are you more positive, or less positive?
Our Creator gives us a defined time here on this planet, and then He empowers us to use that time to become the best version of ourselves we can be. Our reward is the feeling of satisfaction when we make strives toward that goal. That's why a feeling of accomplishment is so fulfilling, it's the reward for doing the right thing. It's our job to honor God by living a life of purpose.
Think about it. Do you know any depressed accomplished people who have chosen to live a life of purpose? I'm thinking you don't. If they are, they've not realized their purpose yet and those accomplishments are aimed in the wrong direction. Depression is a lack of fulfillment. Satisfaction is achieving your purpose.
Isn't it interesting that God created all men, (and women) equal then gave them a choice. We have the option of living a life of purpose or not. A free will is a wonderful thing.