The player who celebrates others’ improvement makes practice a place worth returning to.

A practice where only results get noticed becomes a place people quietly dread, since most of any session is spent being not yet good. Someone who notices other people improving changes what the room rewards: effort becomes visible, and beginners are allowed to exist without apologising for it. That person does more for attendance than any drill in the plan. Groups hold together or dissolve on exactly this.

Say the specific thing you saw someone doing better, out loud, where others can hear. Aim it at whoever is struggling most, and describe the action rather than praising the person.