I think a big part of exercise is being aware of your body and finding the right balance in what you are doing. It obviously varies from person to person. I like to lift weights. I aim for strength and functionality. I also started running, but had some issues with shin splints (I was doing mostly uphill running on concrete) so I'm having to re-approach it.
I would say that back squats and cleans combined with suitcase deadlifts and cable crunches would take you a long way toward excellent skiing fitness. Also hip mobility work in the form of lunge variations, and something to hit the hamstrings really hard.
For overall strength, back squats are hard to beat. These are the core of my workouts. I was recently doing these every other workout, but I am going to switch it up and back off of them for a few weeks to rest. Range of motion is important, but takes time to develop. I generally start with the bar, then gradually put on plates until I'm at around the 3-rep range. I alternate between doing more reps on the lighter sets with fewer overall sets, and less reps on the lighter sets with a bunch of heavy sets. Having a spotter makes a huge difference because you can really grind out some heavy squats without having to worry about failure. Only increase the weight gradually on these, and don't assume that on any given day you can manage a weight you've done before. Gotta' have a spotter for the heavy ones.
I do a lot of heavy oblique work as well. Suitcase deadlifts are really good, as well using a cable machine (low pulley, standing out a bit from it). Both of these work the hips as well. For basic abs, I think I like heavy cable crunches the best. Might as well go heavy on the abdominal work to keep things balanced if you're doing heavy back work.
On days that I don't squat, I either deadlift or do pulls from the floor. I'm not cleaning or snatching at the moment because of an intercostal strain (from front squats). I also like to do deep good mornings with a light weight. I'm not sure about the heavy ones yet, although I've done a few heavy sets with less range of motion and high spotting bars in the squat rack. I'll have to see how my back feels after a few more of those. The light ones with a large range of motion feel really good.
I do a lot of dips with a narrow grip, overhead pressing, rowing, and pullups. Those are the staples of my upper body program. I do some benching and single and dual-arm pushups. I like wide-grip behind the neck presses (I don't do narrow grip ones for safety reasons).
Hip mobility is a big deal. I found this video recently, which is really helping me with my issues: www.youtube.com/watch
. I was doing a lot of single-leg work for a while (lunges and single-leg deadlifts), but backed off a bit recently. I didn't get as much benefit from these as some people espouse, but they are still important.