Peroneal tendon repairs do very well short/long term, and I’ve repaired many in competitive athletes and couch potatoes alike. Posterior tibial tendon repairs do not (as was likely told to you) do so well. Definitely get a few opinions though. Depending upon what is done with modern techniques (synthetic tendon grafts, etc. or a localized FHL tenodesis that ADDgirl had), a PT tendon repair does not necessarily mean a running death sentence. Rehab will be long though (up to a year to return). Best of luck!