I had Haglund's Spurs on both heels, causing calcination on the inner side of the Achilles tendon.
The Peroneus Longus tendon on my right leg/foot had been riding up onto the ankle bone for years (since a "sprain" I'd had had actually ripped the tendon sheath, unbeknown to me at the time).
Had the spur removed from the right foot a few years ago, with the Achilles cleaned up and re-inserted (held in with screws). At the same time the doc took a sliver of bone from my shin and created a channel with it for the Peroneus Longus tendon to run in, curing the riding-up issue. Whilst in there, he noticed that the Peroneus Brevis tendon had a longitudinal split in it, so fixed that.
No wonder I'd been struggling on long runs!
Took quite a while for things to settle down and for me to get back to mountaineering and running, so I decided to leave the Spur on the left foot as it wasn't nearly so bothersome as the right had been. It seems to have settled down so there's no incentive to go for another operation.
Other than that, my feet are great, considering how much I run, and how much time I spend carrying heavy rucksacks over steep/ rocky terrain.