Everything up until now would be pointless if we didn't act on our agreements. Making sure that someone is selected to be responsible for the actual outcome is therefore crucial. Document the agreement and the owner of the task so that it's transparent to everyone inside and outside the team, and so that it's easy to follow up on. It's now up to the owner to execute on the agreement. Of course, she or he can delegate tasks and ask for help so that things get done better and faster.
When the task is finished, report back to your team. This is usually done digitally or in an upcoming stand-up or information meeting. Larger tasks and projects would benefit from a retrospective meeting.