参加活动很积极怎么说英语

To say that someone is very proactive in participating in activities, you could say:
"They are always eager to get involved and take the initiative."
"They have a lot of energy and enthusiasm for participating in events and projects."
"They are a very active and engaged member of the group."
"They are always ready to roll up their sleeves and contribute."
You could also use more specific phrases to describe their proactive behavior, such as "always ready to volunteer," "always the first to raise their hand," or "never hesitant to take on new challenges."