Like you (I'm 41), I started up this go round (after a 10 year hiatus) with a 12/23 cassette and a standard (39/53) crank. Hills sucked! Still, I managed to struggle up them. Then I got a 13/26 cassette. Wow! What a difference. I was able to get up them faster, with a higher cadence, and they weren't quite as painful.

Now I have a compact crank with a 12/27 cassette. It's much better. My speed is up over the other configuration, cadence is higher, HR is a bit lower, and the suffering isn't as great - that is unless I choose to really suffer and pick up the pace. My knees are much happier too.

Got a new bike recently, and went with the same drivetrain config. Compact crank and a 12/27 cassette. It's perfect for me.