Quit being mediocre. You can do better than that.
Quit doing just "good enough." No one has ever succeeded by doing just that.
Quit not striving to be the best. You can be the best for someone, somewhere. Find your niche.
Quit being resigned that you can no longer be the best. You still have time to make things better.
Quit blaming others. From this day forward, take responsibility of your life and own up to your decisions.
Quit waiting for things to happen. Yeah, you know what comes after that. (In case you don't, it's this: Make things happen.)
Quit feeling defeated. You may have lost the battle, but not the war.
Quit staying down. Yes, you may stay down for a while and acknowledge your feelings, but sooner or later, you have to face life again.
Quit feeling entitled. Stop fighting for what you think you deserve. Take what is given to you, be thankful for it, and go! Besides, more often than not, God's grace is more than what you deserve.