Just because I'm competent ...

... it doesn't mean that I want to take over the world.

But lately, people (plural and in two different contexts) have assumed that -- because I'm willing to help with a particular task or organisation -- I'll be willing to take over carrying out or running the whole thing.

Wrong.

I already have more than enough on my plate, and am not doing things I would really like to do. Why would I want to increase my workload of things I don't enjoy, or don't care for as much as other things? I'm willing (in both cases) to take on a little more, but not the whole thing.