If you don’t have strong beliefs, you won’t have the power for flexible persistence. We’ve all heard about Thomas Edison, who performed 10,000 experiments before he perfected the incandescent light. He believed, and he persisted despite 9,999 failed attempts.
You may know of Paul Ehrlich, who tried 605 possible remedies for syphilis. He received the Nobel Prize for his success on attempt number 606. He believed in a remedy for syphilis.