Hi Kim, welcome!
I recently started incorporating exercise back into my daily life as a stress reliever. I put on my "winter coat" this year just like every year--only I put it on top of my winter coat from last year this time. I could definitely stand to lose a few pounds (which is stress relief in itself, amen?).
I asked this same question of my dad and my older sister once and they said "of course you can exercise on Sabbath!" They're not Sabbath-keepers so I instantly thought, 'well, okay nevermind'.
What I did then and what I plan on doing now is changing it up a little bit, especially now that it's starting to be nicer outside. I have no desire to jump on my treadmill on the Sabbath and just stare at the wall, you know?
The plan today is to go to the walking park near our house and pack a picnic for me and the boys. The oldest one already expressed that this will be "lame", but I have a feeling he'll have the most fun out of all of us.
I try to get out into nature on the Sabbath, and now that Spring is starting to poke its head around the corner occasionally, I'm really looking forward to my Sabbath walks, and then those glorious Sabbath naps!
It is very possible to have Christ-centered exercise on Sabbath, and the best part is that it doesn't always FEEL like exercise!
God bless and welcome again!