Submission and domination

Safety tips for sitting on people?

Hello, I didn't really know where to put this topic.

Last weekend I sat on two people, my boyfriend and another friend. I have sat on my Boyfriend a few times but we never had an issue over the 4 years we've been together.

Though now I gotten a little heavy over those years. He showed me red spots from on his arms when I teasingly sat on those and then told me another evening his lower chest was hurting like it was bruised too.

The friend, who had no experience, also reported some soreness the other morning. I sat on them on a mattress on the floor. First I blamed the lack of cushion but my boyfriend got the bruises on his arms on my bed.

If ya'll could give me some tips to not severely injure the ones I sit on I'd be grateful TwT
16 mins