Scottie and Casie love their walks too! I never tracked how long in distance, but we usually have two 30-45 minute walks each day.
They'd probably enjoy a daily run in the fields too. But they don't get that very often as I live in the city. During the summer, I sometimes take them to the open field dog parks though. I tie a long rope, each end to both their harnesses, and let them run together. People laugh and joke that they're taking each other for a run. But really the rope lets me catch them easier if there was some dangerous situation. They know "come", but you just never know. I always hold my breath and pray nothing goes wrong when I let them run off.