Initially go light at 7m workout, that would serve you as a warm up. Once you are able to push, add one more session right after (maybe 5 minute break in-betwee

Initially go light at 7m workout, that would serve you as a warm up. Once you are able to push, add one more session right after (maybe 5 minute break in-between). Your first session stays warm up session. Once 2nd session is not enough (in like 3-4 months), add a third one. Then you can increase intensity of all exercises a bit (still keep the first session lighter). In 1 year you'll be in best shape of your life (given proper food & sleep). Good luck! ;-) Another way to do HIIT is to grab a stationary bike and do intervals there, e.g. 3 minute warmup at low level then increase difficulty or start pedaling faster for a minute. At some point you'd start reducing breaks in between, maybe in 1-2 years you'd do at most 10s low-intensity in-between.