The biggest muscle in your body is very possibly one of the weakest. If you’re spending a lot of time sitting weak gluteal muscles can lead to aches and pains, or worse injuries when you do want to get up and go. Take time to walk through the pictorial or print it off for reference. Two or three times a week and you’ll notice a difference in just a few weeks.
Keep good form through the lower back by keeping the core braced. After every five repetitions “check in” and be sure you’re not sagging as you tire.