I often will do a run two or three times a week at lunch. I have gotten in the habit of doing a rosary by just counting on my fingers starting with my left pinkie and adding with my right pinkie. For the 5th and 6th that are similar to the 4th and 7th Hail Mary when the index fingers and thumbs are touching each other, I cross my thumb and index finger in lieu of finger pad to thumb pad.
This works also for rosary on the run with driving down the road or going for a walk. A great blessing! For the run it works out that the time of the run and the rosary are pretty much the same.