This is kind of strange. Do you practice everyday? (sorry if you have already answered this, I may have missed it).
eg: My mother is 67 years, she was tired ,depressive, did not sleep well etc..I made her changed her bed position to a favorable location (fengshui)and she has been doing zz for 4 weeks everyday, only 10mn (too hard for her to do more)and a self-massage. She feels so much better now, more energetic, don't feel tired anymore, depression symptoms has gone after two weeks ...