"Each one must give as he has decided in his heart, not reluctantly or under compulsion, for God loves a cheerful giver" (2 Corinthians 9:7).
One of the many beautiful things about being part of God's family is the built-in support from the church. A healthy church will delight in helping not only its immediate members but also fellow believers in different locations. Paul discusses this at length in 2 Corinthians, where he encourages the Corinthian church to set aside money for the aid of the struggling believers in Jerusalem.
Paul takes care to make an important point, though: No one should give out of obligation. Gifts are meant to be given willingly; otherwise, it's not really a gift. The recipient will still be benefitted, but the giver misses out on the blessing.
Though Paul is speaking specifically about financial gifts in this passage, the principle applies to any kind of giving. Maybe something requires us to give up our time. We can do it begrudgingly, serving somewhere even though we'd rather not, and making it plain to everyone else that we'd much prefer to be elsewhere. Or we can give of our time joyfully, grateful for the opportunity to help others and showing a little bit of God through our cheerfulness.
This does not mean that, if we can't give cheerfully, we shouldn't give at all. What it does mean is that our hearts ought to rejoice at the chance to give. We can offer up much, even beyond our means, knowing that we serve a God who is able to provide more than we could ever give away. The more we give, the greater our experience of God's abundant blessing. In that amazing way that only God can do, it is to our benefit to give cheerfully!