I don't think you can. This is part of depression: never feeling motivated to do things. My life improved when I began to think like this, because I stopped wasting energy worrying about how to find motivation and how terrible it is that I don't want to do things.

Instead, I followed a few simple rules that seemed to help:

• If I didn't want to do anything, I tried doing stupid administrative work that required no creativity. Cleaning the house. Scanning receipts. Anything that would suck, but at least feel easy to do.
• If I had the impulse to do anything, I did it. Even if it wasn't important. Even if it meant not doing something else important. I just did it. For me, that was often reading, but sometimes it was something creative.
• If I felt good, I didn't have to do any kind do work. I sometimes just enjoyed feeling good for a few minutes or an hour or whatever.

This way, I felt less guilty for feeling good and not working and I felt less guilty for wanting to do something that wasn't important. Gradually, I felt better about my situation. Motivation to do some creative work eventually followed.

I don't know how well this fits your situation, but maybe something in here could help you.

Good luck.