Proverbs 16:2-3 (NKJV)
All the ways of a man are pure in his own eyes, But the Lord weighs the spirits.
Commit your works to the Lord, And your thoughts will be established.
We might consider it pretty bad to deceive people about ourselves. What's worse is when we deceive ourselves. Our good deeds, our giving, our upstanding service all might be seen by the world as wonderful. We could easily convince ourselves too. God looks at the heart. He knows about you things that you don't even know about yourself. We need to allow God to examine our motives and show us what is right.
Do what you do for the Lord and not for yourself or even for other people. This verse says that then you will have the right thoughts with which to plan the kind of work that pleases God. This kind of work will be most beneficial for everybody including you.
Colossians 3:23 (NKJV)
And whatever you do, do it heartily, as to the Lord and not to men,