Seneca, On the Shortness of Life 3.4

Everything you're trying to reach — by taking the long way round — you could have right now, this moment. If you'd only stop thwarting your own attempts.

Of human life the time is a point, the substance flowing, the perception dull... The only thing that escorts a man on his way is philosophy.

Do not act as if thou wert going to live ten thousand years. Death hangs over thee. While thou livest, while it is in thy power, be good.