You can do pretty much anything for your physical activity as long as you do it every week for 3 months, and then another 3 months if you choose to do six months of your physical. If you already go to a sports club whether that be football, hockey or a martial art and you go every week then just do that. You will need an assessor too so maybe just ask whoever runs your club.
One tip I would give is you need to keep a log book every week. You need to do this anyway for your physical, skill and volunteering but I would highly recommend you update it every week with the date, what you did and your assessors signature to confirm this is true. This is much better than not updating it and having to do it all at once and remembering what you did and getting all the correct dates etc.