I've tried taking meetings while on the bike and as soon as my HR gets above about 105 it becomes noticeable to the other party that I'm clearly doing something

I've tried taking meetings while on the bike and as soon as my HR gets above about 105 it becomes noticeable to the other party that I'm clearly doing something exertive. And even though my RHR is about 48-50, riding at 105bpm doesn't even get me into z2 so it's literally just "junk miles"... so I stopped. The joint risk of embarrassing myself + not actually being useful exercise was too much to justify it.