Showing up is good. 'Being there' is better.
Involvement, of course, is what's required. But the word involvement has baggage. It brings on thoughts of costs like: obligation, awkwardness, effort, etc.
A related, and better word is Investment. With investments you get returns!
Be invested in your class and it's interesting, exciting, fun - productive. You know you're invested when a class runs long, you're surprised it's over so soon, and you wish you could stay for another hour.
Be invested in your training and it'll affect your whole world - for the better. You'll be glad you're invested when you turn to your training to help deal calmly with a fouled up airline reservation or when you're trying to survive changing a flat tire in the rain. (Oh, yes, and blocking punches to the nose.)
When it comes to dojo activites, being invested works the same way with one exception. Yet, we don't expect everyone to take center stage.
There are many ways for people take part in the things we do. Some donate cooking. Some take photos. Some watch and listen. And some people really are the life of the party. Surely, all are a part of the group, but more importantly, all are part of the group's great day.