Suggestions for family physical activities?

I really hate exercising for the sake of exercising.  I do 45 to 60 minutes at 3.5 to 4.5 mph on the DREADmill at least 4 times per week and weights twice a week -- but I really hate it.  It's been easy to maintain this since my son is on the swim team and has practices at the Y anyhow -- so I need to fill the time.  

Swim season has just ended.  

I've noticed that my son is very sedentary when he doesn't have his swim practices. I am sedentary other than when I force myself to exercise. My husband is naturally very athletic, but other than physical labor that he does intermittently, he isn't exercising as such.

I would like to add a fun activity to our lives that we can all together that is physically active.  My husband suggested we take ballroom dancing together -- but, truthfully, I don't want to do that because it leaves out my son, costs money, and my husband is so athletic that I will look like an asshat trying to keep up.

I really want a FUN activity that we can do as a family.  I feel if it were something we chose to do as fun thing together, it wouldn't be a chore.  I don't live in someplace awesome like Colorado or Oregon where just walking or hiking is amazing -- I live in the rust belt of America.  That also means that we have 9 months of crappy weather and 3 months of morbidly hot and humid weather.  HAHAHA.
I don't want to shell out a ton of money either.  

Any ideas?

wii 

you can find good games... some of them are very active. 

Pokemon is an option.  It got me and my husband out walking and going to new parks that we'd never have stopped at before.  Maybe you have some cool parks you never knew were around you, we sure did.

Depending on your sons age:

cycling could be an option, there are so many trails and parks set up with shorter and longer loops or degrees of difficulty. And bikes can be found pretty cheap on kijiji etc.

the three of you could take a martial arts class together. Not sure the size of your city, but there's often family classes available. 

Our Y has family days for team sports, like basketball or whatever (this would be my idea of a nightmare hahah)

i don't know if geo caching is still a thing, but it might be worth a google.  Or there might be a newer cooler version of scavenger hunts a la Pokémon style.

If you have access to lakes and rivers, kayak or canoe might be an option. Most outdoor stores around here rent them pretty reasonably and if you love it, apply the credit to a purchase. But there's also tons for sale used online. 

Again depending on his age, you could set a goal to do a charity walk/run together. It would give you a goal to work toward. A lot of them have 1km and 2km ones for kids too.

Nice ideas.  Thanks!

Geo caching is really fun. 

Basketball is available at any school playground. Frisbee golf is popular around here.

I forgot about frisbee golf! I might try that this summer. 

I wish we had frisbee golf in this area -- this is great fun when we summer on the Oregon coast where my mom lives.

We have Metro Parks here that offers practically every activity under the sun, and most of them are cheap. It also offers things like guided nature walks, park clean up and beautification, and other stuff to get outdoors.

We got bicycles cheap and ride them on local trails. We also load up the dogs and take them on different walking paths. They love it, but Lola gets pooped and has had to be carried back.