Lack of persistence is one of the major causes of failure.
Know what you want.
Make a plan to get there.
Set daily activities that support your plan.
What are the things you do daily? The mind absorbs the daily experiences on which it feeds.
If you are fearful, what habits do you have that are cultivating fear? In what environments are you putting yourself? What content are you consuming?
Persistence is a habit you can develop like any other. It starts with a decision. Decide what you want. Create a plan for how to get there. Put in place daily activities that support this plan.
Decide the end result ahead of time. If you persist, you will win.