My best exercise 1990-2019 was step aerobics. Besides the cardio, all the lateral motion was great for skiing. I never felt there was any gradual warmup period for ski seasons those years. Sometimes opening day here means top of Mammoth steeps in high density snow, so you need to be prepared for that.
Step aerobics was a fad in the 1990's, and COVID gym closures killed off the remnant classes at 24 Hour Fitness (free with age 65+ Silver Sneakers). I hike up the hills a block from my house, usually about 800 vertical, and in the warmer months swim laps in my pool. FYI it was 98F at my house today and I swam laps (pool is 72) a month earlier than I have ever done before. Some years with Gray May the pool does not get this warm until June. Forecast is 3 more days of 95+ and a week in mid-80s after that.
Since age 70 I will generally spend half an hour on an elliptical machine after yoga classes.