Leadership that impacts the lives of others does so by setting the agenda. While unexpected events will need to be managed, leadership isn't reactionary. Leadership that is purely reactionary is crisis management.
The reason leadership must set an agenda if it is to be most effective is because if leadership waits for someone else to set it, it departs from its very nature. If someone or something else is setting the agenda, then it is leading the way - not you.
Therefore, if you want to be at your best, do your best work, and lead in a way that impacts others, set the agenda. Determine where the group is going and what it needs to get there. Set a deadline.
Then, get to work. Onward!