Fun & Fitness over 50

Today, I didn't have much time to ride so I did my shortest ride, 10.3 miles and tried to keep my speed at or over 15mph. My usual average speed on rides of any length is just under 13.
This was a moderate workout, not all-out. There are a few rollers on this route, no serious hills, and a mostly flat and straight 2 mile stretch with no intersections or stop signs and little traffic. Good workout on the rollers, powering over them out of the saddle in a high gear, usually the big ring and one of the middle cogs except for the first hill cause it has a 20% or so grade right at the end, just for a few spins of the crank though. Fun!
I was just at 15mph for average speed for the ride and that includes my warm up and cool down so I'm OK with that.
Tomorrow, no commitments; so I'd like to get 30-35 miles in before it gets too hot.