"You can ask a loving God, 'Please let me serve this day. It doesn’t matter to me how few things I may be able to do, just let me know what I can do. I will obey this day. I know that I can, with Thy help.”'
Choose This Day
And another quote by Elder Packer that I like:
"If [you] have a good, miserable day once in a while, or several in a row, stand steady and face them. Things will straighten out."