I'm a pinch older than Dave, and I wonder if the reason I don't have shoulder problems is because I was proactive 25-years ago. My heavy use guns have recoil reducing stocks (a JS Air Cushion in the Skeet gun and a ShockMaster in the trap). Yes, there are other similar systems available, but these guys are in my area. My other guns are fitted with premium recoil pads.
We wear shooting glasses to protect our eyes from immediate danger and we cover our ears for long term hearing protection -- why not long term shoulder protection? If your shoulder hurts after shooting, it's your body trying to tell you something. Why not listen, and do something about it? Fortunately, today's recoil pads are more efficient and there are bolt-on recoil reducing stocks that are far less costly than the custom units.
Yes reducing your load can help, too. If you reload, first select the load data with the lowest pressure for your existing weight and velocity. If that doesn't reduce recoil enough, then consider reducing your velocity. Remember, recoil is based on a factor of the velocity squared, so reducing your velocity 10% gives a greater recoil reduction than reducing the shot charge by 10%.
After you've switched to the lowest pressure load, and reduced your velocity to the minimum acceptable, then consider reducing the weight of your shot charge, as suggested by 1-oz and Dave. There's nothing magic about this process, it's what the ammo makers have been doing with their low-recoil loads for a while.
You may ask, why don't the ammo makers load to the minimum pressure in the first place and reduce recoil in all of their ammo? First, the lower pressure loads may not function in all auto-loaders -- there's a chance your factory ammo is loaded to a higher pressure just to insure that autos will function flawlessly. Second is cost, the lower pressure loads usually require a heaver load of slower burning powder and more powder means higher production costs. So, when the ammo makers use the slower powder, lower pressure loads, they stamp "low recoil" on the box and boost the price. They hit you in the shoulder or the wallet!
Oops… sorry, I strayed off topic. Yes, get a Limbsaver or do what ever it takes. You don't wanna be one of those old gray beards who's got a recoil induced flinch that's so bad he no longer enjoys shooting.