I did my first outdoor run in a while today. Home from my mechanic.
About 3 miles. In 98 degrees of blazing hot sunshine. I too used to run around 6 or 7 a couple of times a week. My knees and ankles had enough of that though. Been running on a treadmill, but miss running outdoors. I think today I may have gotten the bug to do it again.
As others have said, it's important to stretch. I run like 5 minutes, slowly, stretch, then go another 5... stretch again... and pretty much take my time. If I feel I need to walk a little nowadays I don't beat myself up over it. My joints thank me.