You're 52, have a heartbeat and are pedaling. That's faster then a lot of folks
Some good advice has been given above...
CJC puts it right with respect to cadence imho - it's either your legs or your lungs. Try to alternate.
Speed along with the ability to go distances will come in time.
I averaged 10.6 on a ride I did back in June. For that ride it was a decent average. 100Km with 2538 meters of gain.
