What a person, as an individual, can do is limited to one’s capability. However, one has to keep in mind that every action matters.
Every drop matters in an ocean. Every snow flake matters in a snow storm.
The Ramayana tells a story which is relevant. Rama is building a bridge to cross the narrow strip of ocean to reach Lanka, where his wife, Sita, is being held prisoner by the demon king Ravana. An army of Vanaras is bringing in large stones to help in this task of building the bridge. Rama notices a small squirrel also bringing in small stones to help build the bridge. He is impressed by it and blesses it with his hand. The legend is that his three fingers gave the characteristic three stripes on the back of the Indian squirrel.