When we give, we simply entrust to God what we have so he can do something miraculous with it.
Mark 6:38, 41, & 44 (ESV) 38 And he said to them, “How many loaves do you have? Go and see.” And when they had found out, they said, “Five, and two fish.” 41 And taking the five loaves and the two fish, he looked up to heaven and said a blessing and broke the loaves and gave them to the disciples to set before the people. And he divided the two fish among them all. 44 And those who ate the loaves were five thousand men.