A sympathetic Scot summed it all up very neatly in the remark, "You should make a point of trying every experience once, excepting incest and folk dancing."
The lion and the calf shall lie down together but the calf won't get much sleep.
They can conquer who believe they can.
If a cluttered desk is the sign of a cluttered mind, what is the significance of a clean desk?
Let not the sands of time get in your lunch.
Preserving health by too severe a rule is a worrisome malady.
It is better to wear out than to rust out.