Just saying yes because you can't bear the short-term pain of saying no is not going to help you do the work.
Pain s the truth of art. Art is not a hobby or a pastime. It is the result of an internal battle royal, one between the quest for safety and the desire to matter.
Life is not about gutting out every situation. It's about identifying opportunity or the lack thereof. If your pride is all that is standing in the way of quitting, quit. The right people won't care and the wrong people don't matter. If you know you're on the right path, persevere though the pain. It will be worth it.