Starting running at 65

I haven’t run in years ( but I’m an avid cyclist riding about 75-100 miles/ week with climbing) . I started running again. Why ? I like the freedom of it and I can run in places where I can’t ride . oMG didn’t realize how hard it would be . Could barely jog a mile. Any suggestions for older runners? Today I tried 2-3 miles but alternating between running and walking . That seemed to be better on my body . I’m thinking I’ll stick to that plan for a month or two .