68 years old, final month training for Mt.Rainier

I’m a 68 year old male scheduled July 8-11 for RMI’s 4 day Mt. Rainier climb. My basic question is how to utilize the remaining training time. I plan to use my treadmill (15% setting) at Levels 2-3 breathing to further strengthen my legs.

Background: I started with “New Alpinism” in Dec. 2018 and used the 58-Year-Old Novice plan on p. 238 as a guide for endurance. I’m active, as a runner from age 14 until about 5 years ago but continued walking, hiking, and biking. Recently I hiked Mt. Walker, Mt. Rose twice, and Mt. Si, but frequently walked intervals on a 1/2 mile 15% grade section of Capitol Peak Road. I also walk (flat) 2 miles 4-6 times/week.