How do I know if I will be successful? You don't. Anything can happen to you. We're tiny specks of meat on a giant space-rock in an enormous system filled with other space rocks, circling a giant burning fireball of doom.

This system in and of itself exists within an even bigger system and is flying through emptiness at breakneck speed, crashing into other stuff.

And, if science is to be believed, we were a one-in-a-quintillion oops of existence. The fact that you even exist is quite amazing, given the sheer odds the entire human race had to overcome just to get where it is now.

So really, you're already successful. However, if you mean monetary success, just measure how much of your day revolves around monetary concerns. Find a direction and then charge into it until you've got money.

If it's all you do, every day, then eventually you will be successful.