Indisputable
Part of speech: adjective
Definition: Not disputable; not open to question; obviously true
Sure
Part of speech: adjective
Definition: Physically secure and certain, non-failing, reliable.Certain in one's knowledge or belief.
Part of speech: interjection
Definition: Yes, of course.
Example sentence: Today is life-the only life you are sure of. Make the most of today. Get interested in something. Shake yourself awake. Develop a hobby. Let the winds of enthusiasm sweep through you. Live today with gusto.