"Each morning when I open my eyes I say to myself: I, not events, have the power to make me happy or unhappy today. I can choose which it shall be. Yesterday is dead, tomorrow hasn't arrived yet. I have just one day, today, and I'm going to be happy in it."
~ Groucho Marx

"Yesterday's the past, tomorrow's the future, but today is a gift. That's why it's called the present."
~Bil Keane

my favourite,
"If I am not for myself, who will be for me? If I am not for others, what am I? And if not now, when?"
~ Rabbi Hillel