I wanted to know that how one can stop being lazy in religious duties and how can one increase his or her willpower

1- Realize that the infinite hereafter is based on this limited life. Fulfilling every religious duty here will translate into an infinite reward there. And we only live once in this life.

2- Avoid sins as much as possible. Sins deflate our desire to worship God and fulfill religious duties.

3- “Talqin” is very helpful. It is constantly saying to yourself: Allah created me, and so He has given me the greatest abilities. I can do it. Keep telling this to yourself it’s very effective.

You may see this lecture for more practical steps: