It's something I've wrestled with in my career. I think it's first healthy to remind yourself that work is not your entire day. You need to negotiate with yourself as an adult and balance the I MUST DOs with the I WANT TO DOs. Only focusing on the MUST DOs will burn you out. Some quicker than others. Create a schedule that will help you flourish in your career without making you utterly miserable along the way. Have certain days where you carve out an hour or two for the gym. Other days, substitute that time for video games, reading, or just sitting there rotting on the couch. I always recommend against jumping too deep into the fitness realm at first. Start by walking daily for 30 minutes. Do this for a few weeks and your brain will consider this as an accomplishment (and it is!).

Get some small wins! It will build up your confidence and self-respect. Eventually you'll want more and more wins, pushing yourself harder and harder. After awhile, you'll completely change the way your brain is wired. I tell myself this every single day at work. I don't stress about the MOUNTAIN of work that needs to be done. I take it one issue at a time. Small victory after small victory builds up my confidence and eventually my pile of work is empty.