When Do We Stop Serving?

When I was doing ushering that day, one of the uncle said this

Uncle 1 : I think we older 1's should stop ushering and let the younger one's take over
Uncle 2 : Yeah agree. The 1st team got so many young ushers (practically the whole team)
Uncle 1 : Our team all old ushers. Even my wife don't feel like doing ushering as she is always tired.
Jason : *at this moment I had to comments but I started to wonder when do we stop serving*

The thing is this, now the lets say around 30% are doing the 70% job. Last time it was said the 20% is doing the 80% serving. If lets say I decided to say let the younger 1's take over, I guess it will not really happen. Imagine the younger generation will say let the older generation do the ushering while we sit here.

Question to all is, when do we stop serving?