Don't wait for others to do things or take decisions. That's going to be an uphill battle if you really want changes quicker. Start with yourself, and then push others (including friends, family, colleagues, corporations, politicians, etc.). A lot can be done if people take up changes on their own instead of waiting for politicians or corporations or "those other polluting countries" to "just do something" about it.

Here are a few things you can do yourself and encourage those you know personally to follow:

1. Eliminate/reduce throwing or wasting food. Don't buy anything you wouldn't finish eating.

2. Eat only plants, or make plants the largest part of your meals while eliminating or reducing the consumption of animal products. Make sure you read up on nutrition and/or join some support groups.

3. Walk as much as possible and avoid fossil fuel based transport for yourself. Or try cycling. If necessary, take public transport.

4. Promote and use renewable sources of energy, like solar and/or wind, wherever possible.

5. Have fewer children or delay have children a little bit. This may have some other side effects depending on where you live and how the population demographic looks like.

If you think of yourself as committed to this cause and yet you see issues or barriers with the above, that's only a sign of how these things seem impossible to others who don't care enough. Work with (and on) yourself first.

Don't be shocked or surprised: you will see a whole lot of apathy all around you. People will even try to discourage you from doing anything and try to convince you that whatever you do just doesn't matter. Stop looking at them or listening to them.