On his own Billy would have stopped long before he finally slowed, but he felt an embarrassingly strong desire to impress Bucky. One that felt especially stupid in moments where he had to be bodily helped over obstacles. (But GOD, he didn't know how much his body would respond to being picked up with such easy before today either.)

He clearly didn't want to admit he needed a break, trying to distract himself with idly chatter, though eventually it felt as though he had weights strapped to his feet.