Health impacts from low gravity will likely pose a problem for Mars colonists. There have been a number of high-tech and rather improbable proposals to address this, such as building entire colonies on high speed trains running around circular tracks.
A much simpler "low tech' - if perhaps only
partial - solution, would be to build large, circular, bowl-shaped chambers for colonists to ride around in on bicycles, both getting exercise and creating artificial gravity for themselves.
The bowl shape is needed to allow riders to get up to speed, as at full speed they would literally be riding on the walls of the chamber, while at low speeds (starting out and end of ride) they'd be riding closer to the flat center, and a smooth transition between the two is needed.
Just as astronauts on the ISS gain some benefit from working out a couple hours a day, the colonists should benefit from a couple periods of higher gravity a day. Combined with already having about 3.7m/s^2 constant gravity on Mars, the net benefit should be greater than working out in zero-G. To achieve 1G (9.8m/s^2) at full speed, in combination with Mars' own gravity, the bike rider would need to achieve about 9m/s^2 outward acceleration.
Dizziness is a potential issue. Most of dizziness results from head movements out of the plane of rotation, so bike riders could train themselves to minimize such movements. Increasing the radius of the chamber could also help, but comes at the cost of needing to ride faster for the same amount of artificial gravity.
Riding at 5.2m/sec (~12mph air speed measured at the rider's center of drag area, roughly 1m off the room's surface), one would need a chamber of about 8m diameter, which might make it harder to avoid getting dizzy.
A chamber 18m across would require one to ride at about 8.5m/s (about 20mph), but that might be practical for long rides if air jets make the air in the chamber spin around at about 7mph in the direction of the ride to reduce wind resistance. Alternatively, one might use electric power boosted bikes to make long rides at 20mph practical. That could also insure that older colonists can still keep up the pace needed for a full 1G ride.
Boredom would be another issue that needs to be addressed, to insure the colonists keep doing it. One possibility would be to project scenes onto the chamber floor and ceiling, creating the illusion of riding a bike path through a forest, a desert trail, etc. Another possibility would be to have two or even three riders in the same chamber, so they all have to be constantly paying attention. That might evolve into competitive "chamber bike racing". The downside of that would be potential collisions, of course...but a bit of risk would also enhance the experience.