Where to start.... You must do rotator cuff exercises- especially external rotators (with band). These help align shoulders. Don't stretch rotator cuff- they are small/weak muscles often already stretched. You must stretch pecs- especially if you work at a desk. Also calves, hammies and hip flexors. Do lots of pulling knee to chest/opposite shoulder, especially if stiff through hips- helps with pop up. Use a foam roller under thoracic spine, once again desk work is the culprit here. Lift weights- mainly exercises that not only use a lot of muscles, but create functional strength. Squats, pull ups, bent over rowing, bench press (but stretch those pecs...). Drink heaps of water. Stay off foods that inflame (sugar). If you need surgery- get it done by the best orthos you can find. As you get older, you get bone spurs/ deposits that can fray rotator cuff tendons under the acromion. The AC joint can become arthritic due to overhead nature of paddling. They grind off the last (in my case 15mm) of collar bone. Works well if you are meticulous about rehab including rotator cuff exercises. Ride big, buoyant boards that allow you to catch waves easily and keep you high up out of the water when you paddle. If you really want to hang on to your youth and ride shorties go for volume, flat rocker and adequate width (shameless plug for Geoff McCoy's boards!) . Avoid 'lizard paddling'- paddling with chin close to deck- work on thoracic spine flexibility. Look at the groms- they get an almost 90 degree bend from thoracic spine through the neck- even on a shortboard they have shoulders lifted up high as they paddle. Keep your surf sessions sensible. Do laps in the pool. Practice swimming/kicking with flippers without breathing- you'll thank yourself next long hold down. Know your limitations as to wave size, ride 'em big enough to thrill but not scare. If you are an elder statesman (or woman) act like it. Support groms/women/learners/strugglers in the water. Stand up to those who don't. Give waves away; keep egos in check. Smile and say g'day to other surfers. To quote Gerry Lopez- 'surf today like you are going to surf tomorrow, not like there is no tomorrow' (or something similar). Another quote worth mentioning, from baseball- 'that arm only has so many throws'. I'm no doctor, so don't take any of this as gospel, but all this has worked for me. 54 and as stoked as I was at 16.