I need to add some HIIT to my routine. I currently only do walking (although this includes uphill walking), and am probably not in great shape as far as HIIT kind of exercise. I read the threads related to HIIT and Fitness Blender and these seem like good places to start. I googled beginner HIIT both on Fitness blender and on youtube. Just wondering if anyone has any specific recommendations about how to start; some of these look hard for me and I do have some knee pain (nothing serious, but I don't want to aggravate it).

Also, if you use Fitness Blender, do you have any tips on how you make use of the site? Do you sign up, use the calendar, do anything else or do you just google what you want?

Thanks!