A true giver is not motivated to give simply because he anticipates reaping a prosperous return on his investment. A generous person gives to the work of the kingdom because his heart desires to give. He loves God and wants to do everything he can to further the work of God on earth.
In Exodus 25:2, the LORD asked Moses to collect donations only from those donors who desired to give: "From every man whose heart moves him you shall raise My contribution" (Exodus 25:2). The collection was to be a free-will contribution, not an imposed tax or even a tithe. Tithes are important, but terumah is supposed to be given simply from the heart.
This can be compared to a husband and wife who loved their son and wanted to see him succeed in life. Though they depleted their savings to send their son to college, they did not regret the loss at all. Instead, they desired to help their son get a good start in life, and they rejoiced to be able to do so. In the same way, a person who loves God should be eager to do all that he can to see God's work succeed. When he invests in the kingdom, he does not regret the loss. He sees it as an opportunity to fulfill his hopes.
A true giver wants to honor His Father by giving back from the resources bestowed upon him. The true giver does not think of his money and his resources as belonging to him. He regards all that he has as belonging to the LORD. Therefore, when he gives to the LORD's work, he feels no regret.
This can be compared to a wealthy man who was going on a journey. Before he left, he entrusted his neighbor with a sack of money for safekeeping. On returning from the journey, he asked for the sack of money back. The neighbor felt no ill will about returning the money because he was only the custodian of it for a short while. In the same way, we should regard all that we have as belonging to God.
A person who gives to the work of the kingdom should do so willingly and gladly. The Apostle Paul says, "Each one must do just as he has purposed in his heart, not grudgingly or under compulsion, for God loves a cheerful giver" (2 Corinthians 9:7).