Trying to get back into running and it's humbling

Used to run half marathons in my 20s. Tried to do a 5k loop yesterday at 35 with 20 extra pounds and two kids. Made it 2 miles before my knees were begging me to stop. My 7yo on his bike was actually lapping me. THE IRONY. Anyway, I'm starting Couch to 5K like a beginner bc apparently I am one now. Anyone else dealing with this comeback struggle?