There are physical activities that require equipment. Depending on the frequency of the undertaking, it may be a good idea to purchase that equipment...or it may be a good idea to simply rent it...kayaks, snowboards, and ice-skates used only 1-2 times per year would be good candidates for renting. There are no physical or mental space considerations, upkeep, replacement, or regret involved with rentals (well, maybe regret...but it's probably less). :) And don't hesitate to list that unused exercise equipment on craigslist...it might be just the thing someone else is looking for.
There are a lot of activities that we can do for exercise with quite a small amount of (or no) extra clothing or equipment. I love the idea of playing soccer, basketball, or volleyball as a family or group of families...all that's needed is a ball + a walk to the park. It's family time, exercise, and time spent growing friendships too. Make it a biweekly or weekly "scheduled" game + there are no team fees to pay either.
Our (the girls' + my) personal choices are walking (quickly) + yoga. Cardio, strength + flexibility building...addressed. My necessities are shoes + a yoga mat. As far as athletic wear goes, I wear leggings (I have 2 pairs that I wear for everything) in the winter. For the summer, I have two pairs of athletic shorts + two tanks.
I recently added a pack of yoga cards to my workout gear, because videos are always catching me twisting awkwardly to see the screen + not always feeling like I've gained the full benefit of a movement before moving on to the next. I really like these cards, because it is possible to lay out a personalized progression + there are suggestions for different workout objectives as well.
For arms, I do swan arms in lots of different positions. I wasn't feeling much bicep work, so I bought these resistance bands with interchangeable bands for increased resistance over time. They take up less space than barbells + I won't have to keep buying bigger ones.
After Monday's fair athletic wear post, I hope it's not too late to say that an excuse to buy new clothes or stuff is not the point of exercise. :) The lists posted here are meant to be tools available when they are needed...not promoters of wantiness or ethical justification for excessive purchasing (easier said than done, I know).
The idea here is not to recommend things to buy, but to encourage thoughtful consideration about the activities we choose to add to our lives and the things we choose to add to our homes. Time spent with our partners, kids, and friends can be a great part of exercise. Seldom used stuff need not be.