So I posted a little bit ago about hanging a punching bag from the rafters.
I have the bag on a fixture mounted to 2 rafter beams (the rafters are roof
trusses, 2x6's). The bag is a 110lb bag, hanging from an eyebolt . The
issue that I'm seeing is that when I punch the bag, the whole ceiling is
moving. I don't mean shifting off its mounts of course, but rather I can
see the ceiling drywall moving back and forth and rocking in tempo with the
bag.

It's not like I'm Rocky Balboa or someone, but I'm a pretty strong guy and
110lbs is a lot of weight. So I'm looking for some advice/options for my
concerns. My concerns being that I'm afraid that if the ceiling is moving
enough for me to see, that means the whole structure is under way more
stress that it can take. But what to do about an object that weighs that
much but has to hang from 9 feet in the air. The rafters in my house are at
exactly the right height.

Could I build up the rafters at the location where its suspended, add a
second 2x6, add a lot more cross bracing between the two rafters its hung
from, something like that. Admittedly I didn't do a lot of mod to the
hanging point, not knowing how it would respond I chose to take it slow and
see if this was feasible or not.

Right now the eyebolt is hanging from 2 2x4's with a 1/2 plywood sheet on
top across 2 rafter beams. I believe MeatPlow offered that suggestion up
last time I posted this. Give a little more effort I could make a better
suspension jig, maybe 3 2x4's (hole for eyebolt in middle board), 1/2
plywood to tie them together on top.

I don't know, what do you all think?