Kalidasan

“It is not that we have a short time to live, but that we waste a lot of it. Life is long enough, and a sufficiently generous amount has been given to us for the highest achievements if it were all well invested. But when it is wasted in heedless luxury and spent on no good activity, we are forced at last by death’s final constraint to realize that it has passed away before we knew it was passing. So it is: we are not given a short life but we make it short, and we are not ill-supplied but wasteful of it… Life is long if you know how to use it.”
― Seneca, On the Shortness of Life: Life Is Long if You Know How to Use It

“In the first 30 years of your life, you make your habits. For the last 30 years of your life, your habits make you.”
― Walter Isaacson, Steve Jobs

“Most people die at 25 and aren’t buried until they’re 75.”
― Benjamin Franklin (attributed, not found in any major work, fake)

“Don't let your learning lead to knowledge. Let your learning lead to action.”
― Jim Rohn