At 68, I'm entering my 4th year back on the bike. I tried riding all winter last year but found it just too demanding. Since I basically refuse to work out indoors, I thought now that I'm down down 85 pounds, I'll try running again this winter, which I did.
I eased into it very carefully and do a lot of walking. When I ran previously, walking was failure, now it's a reward. My technique is to set a pace for the run then every half mile I check my time, the balance I come in under the pace, I get to walk until I hit the time. I'm walking anywhere from 30 to 120 seconds every half mile for 6 to 10 miles. Beating me up a lot less then steady running and I'm enjoying it more.