This is very strong.

The Vilna Gaon taught that if you are 100% determined to do something good, there is no room for the Yetzer Hara. If you believe you can do it, you will do it!

The problem is we want to keep the door open for our own comfort so we can escape.  But by leaving the door open, we let the Yetzer Hara in!

So close the door to the questions!  You cannot allow in any room for confusion.  Only when you decide to leave that opening does the Yetzer Hara come in.  Close the door!  ~ Adapted from a shiur I heard from R’ Avraham Moyal Shlita