Understanding that successful people do need persistence to achieve success will inspire you to be persistent yourself. So find and read the life stories of successful people throughout the history. While most people recognize them only through their achievements, by reading their stories we will understand the persistence they need on the way to success.
One of the main reasons people giving up early is having wrong expectation. They expected the way to be easy, and they are surprised when they find the reality to be the opposite. Their enthusiasm quickly melts and they lose heart.
So start your journey with the right expectation. As I wrote above, there is no such thing as cheap success. Expect a hard way, not an easy one, and you will be mentally prepared when you encounter the reality.
Just like you should not underestimate the difficulty of the journey you are about to take, you should not underestimate its length either. Of course, everyone wants to achieve instant success. But this, unfortunately, is not realistic. The journey to success is a marathon, not a sprint, so prepare yourself accordingly.
To keep your persistence, you need a strong source of motivation. How else can someone keep trying again and again without strong motivation? And such strong motivation comes from your purpose. You should know why you want your goal in the first place. And your why must be bigger than the obstacles. The bigger your why the better.