Never tell a young person ...

Never tell a young person that anything cannot be done. God may have been waiting centuries for someone ignorant enough of the impossible to do that very thing.
 G. M. Trevelyan

Quotes from the same author

The best job goes to the person who can get it done without passing the buck or coming back with excuses.
 G. M. Trevelyan
Education... has produced a vast population able to read but unable to distinguish what is worth reading.
 G. M. Trevelyan
I have two doctors, my left leg and my right.
 G. M. Trevelyan
After a day's walk everything has twice its usual value.
 G. M. Trevelyan
The chorus-ending from Aristophanes, raised every night from every ditch that drains into the Mediterranean, hoarse and primeval as the raven's croak, is one of the grandest tunes to walk by. Or on a night in May, one can walk through the too rare Italian forests for an hour on end and never be out of hearing of the nightingale's song.
 G. M. Trevelyan