Volunteering can take up as much or as little time as you’d like. It differs from paid employment, where your hours will probably be set by your employer. As a volunteer, it’s up to you to decide how much time you’d like to give.
If you’re already playing sport, you could ask your club if they need any help. You might want to do voluntary work before or after you play sport at the club, which will save you travel time and is a great way of getting to know the people at your club.
Be clear about how much time you want to volunteer, so that expectations are set properly from the start. There might be lots of little jobs that need to be done at your club and, if everyone does a little bit, it could save one person a lot of work.