Never discuss it. Just say: the doctor prohibited raising more than 3 kg and that’s all. This is an objective reason, not just a weakness.

As if that was enough. Variants of real answers to my explanation that doctors have forbidden me to lift heavy:
Lie to
I’m a doctor too and I’ll let you.
Just invented it?
Everyone’s going to go, but you’re not, don’t you feel ashamed?
The smartest thing?
Show the certificate
Finally broke out

Previously I was lost, now I just send us