Whenever you do your cardio by walking, throw in some walking lunges as well
to boost your glutes and set them on fire,especially if you go uphill.
Next time you are out walking, you will do walking lunges in every uphill you go.
The longer steps you take, the better glute and hamstrings stress you will get.
When you walk..try to squeeze your butt in every step you take,so when you start to walk with your right leg,and then switch to the left leg,squeeze your right glute hard before you switch to the left one.
You will simply squeeze the butt cheek on that leg that is extended behind your torso.