I never was a very good long distance racer and now I am worse. I kept thinking this past winter my asthma and other respiratory stuff was getting worse. You know short of breathe even after taking a nebulizer breathing treatment. Now I know it was my old ticker trying to tell me something. When it had had enough it darn sure let me know! It felt like a city bus loaded with elephants sitting on my chest and left arm.  
 
I tried going out yesterday to do intervals. After the first one I knew it was a no go. Geez, everything is hard for me to do now. My can do sure can't keep up with my want to! I was bad on hills before and now am way worse. Maybe time for e-assist for hills. Riding on the flats is no problem but even slight hills make my old ticker hurt. Maybe the TSDZ2 with the 72 volt over drive battery will be the answer! You still have to pedal for it to work and I have read where guys turn the magnet sensor around 180 degrees when they didn't want or need the motor to engage.  
 
I am still trying to figure out a way to get one of my doctors to turn the cost of the battery and TSDZ2 into Medicare as a consultant fee!
 

Man i know it's not the same thing but i couldn't do 5 miles without feeling like i was going to explode. I had significant loss of lung function and on inhalers and the like  Flat ground felt like a hill unless i was getting 30 percent motor assistance. What helped me was swimming. though i could barely do that at first i improved very slowly. I think the breath holding helped tremendously.  Took about 6 months before i could get past that 5 mile mark.  You will get it back. Just don't push yourself too much!