I practised this a lot (slowly) after an operation for prostate cancer. I didn't appreciate how hard it was just to take a short walk down the road to the shops. I had never felt so tired just taking a few steps.
The advice from the doctors was that walking was the best exercise. And they were right. I did this exercise and others that involved simple stepping patterns and standing on the spot. Gradually I was able to build up my stamina and tackle longer walks.
After four months I returned to doing my form practise.