Coming from someone who just started this morning, I started a plan to walk anywhere between 5 plus minutes. I’ll do this each day. I’m no runner, but I enjoy going for swims in the hot summer weather.

I do kickboxing and tabatas. If you are looking for something slower/low impact, try anything where you have to get up and down off the floor, like alternating toe touches, bear crawls, burpees, mountain climbers, standing ab moves, and arm circles. You can use a light weight to do swimming motions too.
I struggle to run more than 3 or 4 minutes on the treadmill, so I just do 4 minutes of running and jogging, walk for the last minute, then I go do some weight training or something for awhile, then come back and do some more running.
Also keep in mind that most bodyweight moves will get your heart rate up same as cardio. You could try marching in place, then do prisoner squats, walking lunges, push-ups.
I hope this helps.

Check out Bodyfit by Amy on Youtube - she has great cardio workouts!

I ran and jogged for many years but back problems have forced me to stop. I know bicycle. I'm fortunate that I have access to miles of jogging and biking trails here in Tulsa. I highly recommend it. For winter I plan on do cold weather rides and using my health clubs stationary bikes.

On YouTube there’s a channel called MadFit you should check it out I love her workout videos, She has lots of cardio videos that don’t involve running or swimming