One of the best insights in the book Switch was the observation that when we have a crater-size problem we tend to look for crater-size solutions. The authors point out that this is a mind trap: there's absolutely no rational reason we can't fill a crater with small stones.
There are a lot of situations in life we can approach one pebble at a time. In fact, with the bigger problems we have to do this. We aren't strong enough to heft boulders and meteorites. We often don't know where to find them. And there are pebble-size things everywhere.
Sometimes when we face great difficulties we feel helpless because we can't do anything substantial to make things better; the only things we can do are at the margin. There are two things I'd note about this:
First, wounds heal from the edges. They don't heal all at once; they start healing at the margin. If you can do something about the margin, it matters.
Second, what happens at the margin isn't always visible. What you do isn't going to give you the kind of satisfaction you get from cleaning a closet or painting a wall. Nonetheless, it matters.