In the classic book, The Greatest Salesman in the World, by Og Mandino, there’s a chapter/theme called:

“I will persist until I succeed”

Within this, a couple of passages stick out, that may be relevant to you.

“It is not given to me to know how many steps are necessary to reach my goal. Failure, I may encounter at the 

thousandth step, yet success hides behind the next bend in the road. Never will I know how close it lies unless

I turn the corner”.

and

“I will consider each day’s effort as but one blow of my blade against a mighty oak. The first blow may cause not

a tremor in the wood, nor the second, nor the third. Each blow of itself, may be trifling, and seem of no consequence.

Yet, from childish swipes the oak will eventually tumble.”

Maybe this helps keep you going…