To answer your question that you asked: no, this is not a matter of being too old, and improvement is possible. How much you can improve is a different issue.
This is a different expert. I am a double board certified clinical doctor doctor. I have been responsible for pulmonary and heart patients, beginning to end, for over 20 years.
to answer this question accurately, I need some test results.
Can you put in your pulmonary function test results.
Have you had an echo cardiogram: please put in the report.
These assessments must be done to answer your question of how much you can improve
[Find me in medical anytime by request, as you might have future questions.]
And, why the Pulmonary embolisms?
The underlying cause here needs to be delineated as well.
You should not exercise at all until that is explained, where are the clots coming from. Are you on blood thinners?
If they are from your legs or pelvis, this needs to be addressed first.
Finally, do not start using the lung boost until cleared by your doctor. This is an aerobic training program and should be supervised.
Please click a positive rating on the rating scale for Dr. Thomas.
Please let me know your test results.