I would recommend a brisk walk rather than the " fast as you can" walk this has greater cardiovascular benefit for you and appears to place less stress on your respiratory status.
I am 20 years old and was diagnosed with hypertrophic cardio-myopathy 6 years ago. I was told to abstain from all strenuous activity, especially weightlifting. I have complied for the past 6 years, but have become depressed about my situation- and was put on anti-depressents. I have recently become weightlifting and have felt psychologically better than ever. I feel the benefits from working out, may possibly outweigh the risks. (Incidentally, my doctors have never detected an arrythmia from my Holter monitors.) I would greatly appreciate it if you could respond to me on this matter. Thank you.
I would recommend a follow up visit and consider a reevaluation with a test called a exercise echo to document your heart function at rest and with exercise.