Don’t depend on it.
You are weak. If you depend on willpower, you will falter, and you will falter often. Your dreams will fall by the wayside as you find yourself unable to sustain persist the long-term. You will be crushed, and it will be your fault.
Don’t feel bad. I’m weak too. That’s why I spend so much time thinking about tricks and tactics that don’t depend on willpower, or minimize its effects. I am weak, and I know that, so I approach my problems from a position that minimizes my weakness. I approach from where I am strong, or stronger.
If you have to force yourself to do something, eventually you won’t. Instead, work on making it easy. If you can establish habits that make it easy to get started, then you will. You won’t have to burn your limited willpower so much. You won’t get tired. You won’t depend on it. That’ll make you more likely to succeed.
Rather than depend on willpower, set it up so you don’t have to.