I don't think you can ever do your best. Doing your best is a process of trying to do your best.
Townes Van ZandtBroadly speaking, the short words are the best, and the old words best of all.
Never Give In!: The Best of Winston Churchill's SpeechesThe best time is now. The best thing to do is what you are doing. So do your very best.
Debasish MridhaThe best use of life is love. The best expression of love is time. The best time to love is now.
Rick Warren