Both sentences "I’m boring" and "I’m bored" are grammatically correct, though they mean very different things. The –ing ending means you are changing a situation, and the –ed ending means the situation is changing you.

If you are boring, then other people don’t want to be around you – you change them / bore them.

If you are bored, then something / someone near you is changing you and your feelings.

All of these pairs (e.g. tired / tiring, excited / exciting) are formed from verbs:

• John bores Mary, so

Mary is bored.

John is boring.