How many: 10 reps with right foot leading; 10 reps with left foot leading. 3 sets.
How many: 10 reps on each side. 3 sets.
How many: Keep walking for 60 seconds; rest for 30 seconds; go again for 60 seconds. Hold a heavy object in front of you or on either side for an extra challenge.
How many: 10 reps x 3 sets. Hold a heavy object in front of you for an extra challenge.
How many: 10 reps on each side. 3 sets.
How many: Continue for 60 seconds; relax for 30 seconds. Do 60 seconds more.