I am 30 and its all about being in shape. Hell, Candide is 36 and Tanner is 35. I have been doing kettlebell exercises and can rip harder than I did when I was 22.
A good routine is to do this kettlebell workout every other day then do a yoga exercise and stair jumps the off day. I recommend the Rodney Yee A.M. Yoga DVD and this kettlebell workout:
For stair jumps just go to the stairs in your house and jump up 3-4 stairs at a time then walk back down and repeat until you are too tired to do it clean. Also focus on keeping your eyes up which will help your form.
The Kettlebells will build muscle and stability and yoga will keep you flexible to avoid injury. Kettlebells actually get your ripped really quick too, when I started my routine I found all my shirts started to fit tight in about 2 weeks. As for progression, focus more on your form and once that is dialed in you will find even challenging runs to become easier and easier. One nice thing about being over 30 is that you can enjoy skiing for what it is and not have to have something to prove which is a mindset I kind of had in my 20s.