[It's a very general answer to a very general question—ask and you shall receive, but it makes Tifa smile as she digs another small hole for more seeds so he can continue to water down their little line.]

Making a difference can be something as small as planting some fruits, or changing the world.

[She dusts her hands off and anchors them on her knees so she can grin up at him.]

I think you're off to a great start.