“And let us not be weary in well doing: for in due season we shall reap, if we faint not.”
Galatians 6:9

When you do good to others, do so buoyantly and with joy, because the word of God already set your expectations- he has said you would reap, and he encourages you to sow bountifully:
““Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap.” Galatians 6:7
“But this I say, He which soweth sparingly shall reap also sparingly; and he which soweth bountifully shall reap also bountifully.” 2 Corinthians 9:6
Do good to others, not because they are nice to you but because the word of God says you should- and so your joy should be in the fact that you are living true to yourself- you are doing God’s word, rather than you are giving to others primarily.
“…The same with good deeds. Some you see right off, but none are hidden forever.” 1 Timothy 5:25, The Message Bible