This yoga should be practiced with firm determination and perseverance, without any mental reservation or doubts.
Bhagavad Gita
If your determination is fixed, I do not counsel you to despair. Few things are impossible to diligence and skill. Great works are performed not by strength, but perseverance.
Samuel Johnson
Determination and perseverance move the world; thinking that others will do it for you is a sure way to fail.
Marva Collins