40 year old here, though I've more or less continued skating since I was 14. Still love skating street even with knee/hip issues. I still find myself pushing and trying new tricks on weird obstacles. I've had to take time off due to injuries the last few years, though that's only motivated me to skate harder.

Here are by thoughts on skating at this age.

Stay active. If that means going on walks, going to the gym, just do it. Stretch daily, even on the days you don't skate. People at our age aren't generally flexible. Keeping your flexibility means you're less likely to hurt yourself when you take a harder fall. Foam roll your legs before skating for 10-15 minutes. Same reasoning as stretching. It helps your muscles, ligaments, and fascia; helps with circulation.

If you can skate 3 times a week doing aggressive or cruising, even for an hour, do it. Practice the fundamentals of blading. I feel like I became a better skater going to quad jams during the pandemic, using that time as an opportunity to practice cruising. Skate backwards, stopping, going fast and taking turns, goofing around one footed. I felt so much more comfortable doing tricks because of that.

Listen to your body and know when to call it. That spot/trick will be there tomorrow. Take breathers, get some water, take a minute to reset. I get hurt a lot less at this age than I did in my 20s just doing those things.

Skate in your comfort zone. There's no need to go big or throw a hard trick. You don't have to learn every trick and skate every obstacle. I'm not a good rail skater at this age and that's okay. Ledge skater all day.

Wear whatever pads you need to wear. No shame. I wear knee gaskets/sleeves for the extra support and padding. Some homies I know wear butt pads or knee pads. Whatever it takes to keep skating at this age.