Did TBT for 28 days, repeated TBT and on day 18 of second month. Getting great results, lost 10 lbs. and sticking to the diet. I am 57 w a bad knee, so jumping and twisting are difficult. This weakness keeps me at Level 1 on TBT, but I would like to try something new after current round of TBT is up. Any suggestions for old guy w "great desire" but "bad knees".