He that complies against his will, is of his own opinion still
If you force someone to do something or agree with something, it doesn't mean that they really agree.
He that wills the end wills the means
If you are determined to do something you will find the way to do it.
Never spur a willing horse
Don't urge someone who is already working well to work harder and faster. If you do, he may work less hard or be less eager.
No pain, no gain
If we do not do hard work, and suffer some pain, we will achieve or gain nothing.
None so blind as those who will not see
Nobody is blinder than the person who decides he does not want to see. Often used in reference to prejudice and intolerance.
None so deaf as those who will not hear
Nobody is deafer than the person who decides he does not want to listen. Often used in reference to prejudice and intolerance.
Nothing is impossible to a willing heart
Someone who is eager, keen and determined can achieve anything.
The spirit is willing, but the flesh is weak
Even though we may want to say "No" to temptation (doing something bad), our body may be unable to resist it.