Dear Waves,
I'm happy that your feet are cooperating with you.

Here is my suggestion -- not that I claim to know this stuff:

Walk more than you have been doing (briskly or otherwise) and keep track of
1. distance
2 time of day or other variables you think relevant
3. your speed /effort
4. breathing and heart rates at various time you deem appropriate.

You can keep track of what is happening here at our site.

Talk to pdoc and let him give you the go ahead to start a walking routine. Work on getting a better cardio look see from an md who cares about people.

Keep monitoring the Zoloft reactions.

M.