Maggie's Farm

If we're talking about building lower body strength and power (as opposed to endurance, agility, etc),  then you really need to do things like barbell squats and deadlifts.  Men and women, all ages. Walking and running do nothing to improve lower body strength.

For ordinary "functional" fitness, lots of people skip the weights and do body-weight lower body strength workouts. These are the basuc things you need to hike up hills all day. Body-weight Lunges and Squats . And although Stair Machines are usually considered a cardio/endurance activity, they are a body-weight lower body muscle stressor for sure so I consider them cardio/calisthenic if done at a good intensity.

Predictably, I come down to my usual recommendations: Do all of it: Weights for strength and bone,  cardio for heart, endurance, and stamina, and body-weight exercise/calisthenics for everything. 

This 15- minute set of leg calisthenics with no breaks from Mindy looks good and tough. I would find it challenging at the least. Feel the burn. An hour of calisthenics like this will make you feel great the rest of the day.