Use It Or Lose It Quotes by Hippocrates, Samuel Beckett, Richard Bach, Alfred North Whitehead, Carolyn Heilbrun, Susan Sontag and many others.

That which is used – develops. That which is not used wastes away.
Yes, in my life, since we must call it so, there were three things, the inability to speak, the inability to be silent, and solitude, that’s what I’ve had to make the best of.
Perspective – Use It or Lose It.
The only use of knowledge of the past is to equip us for the present.
That is the point of quotations. One can use another’s words to be insulting.
What we need is to use what we have.

We have more than we use.
Ranger declined the butterscotch pudding, not wanting to disrupt the consistency of his blood sugar level. I had two puddings and coffee, choosing to keep my pancreas at peak performance. Use it or lose it is my philosophy.
The true use of speech is not so much to express our wants as to conceal them.
The ability to concentrate and to use time well is everything.
We must use what we have to invent what we desire.
Money is like an arm or leg – use it or lose it.

Writing is the only profession where nobody considers you ridiculous if you earn no money. Money is like an arm or a leg; use it or lose it.
Use it or lose it is a cliche because it’s true.