I don't like letting people down. 

I feel guilt and shame when someone says "you promised" .....

But what I know I can promise .... is simply to try. Not anyone else's definition but my own. 

And just try. 

I'm afraid to even say "my best" .... because I don't want to get trapped into an idealistic perfectionistic "try" that is frankly impossible. 

Do what I can. And that's enough. 

I promise to try. 

and then be specific. What I can do. I can try to think about it. I can try to take a first step toward it. I can simply TRY.