Has anyone returned to full mobility?

I used to be super active. Had a mild floxing 7 months ago (plantar fascitis, achilles tightness, the works) I want to be able to run marathons and triathalons again someday. Will I ever be able to do that? I’ve been feeling awesome most days- walking, etc. I would call my healing so far incredibly successful. Will I ever be able to engage in intense exercise again? How and when do you start?