There's nothing like helping someone else in a time of need. It takes you out of whatever you are stewing on, assists someone that couldn't get it done by themselves and leaves everyone in a better mood. Why wouldn't you want to experience that?
If you've noticed, there is trash everywhere. It piles up when people throw their cigarette butts out the window or push all the empty bottles and wrappers out of a car into ditches. Don't even get me started with the discarded needles and random loose shoes...