Disappointment

How am I supposed to lift the spirit of my disappointed brother when I myself can't even set the example?

When God closes one door, He opens another.
It will be a few failures for us to learn the lessons we need to succeed.
It's okay to make a mistake, just learn from it and never repeat it again.
You're fine the way you are. Just keep doing your best.

Those are lines that I keep repeating to myself, but I always catch myself questioning their validity.
Exactly when will He open the door? Why don't I see any right now?
Yeah, how many failures does it take for ONE success then? Hundreds? Dude, I'm no Edison!
No it's not okay to make SUCH A GRAVE mistake! -,-
What if my best isn't enough?

I feel like a hypocrite, telling those to my brother and not believing in them entirely myself.