Never ride a bike with the brakes on. If something is proving too difficult, give up and do something else. Try to live without resort to perseverance. But writing is all about perseverance. You've got to stick at it. In my 30s I used to go to the gym even though I hated it. The purpose of going to the gym was to postpone the day when I would stop going. That's what writing is to me: a way of postponing the day when I won't do it any more, the day when I will sink into a depression so profound it will be indistinguishable from perfect bliss.