And if you can't get out there to pick up trash you can also help on a daily basis by recycling. I've been recycling for years and you'd be amazed how much less trash you generate when you are sending everything you can to be recycled and used again and again.
Also, try to buy products that come in reusable containers, or find a container that you can use repeatedly rather than buying someting in a container you'll throw away. Plastic water battles are a real problem in land fills. Instead of buying plastic water bottles get yourself a plastic or metal bottle that is meant to be reused and use that instead.
There are a lot of ways taht we can help clean up our planet if we just get creative.