Go from Boot up the bridleway to Burnmoor tarn but don’t head over to Wasdale, instead turn left into Miterdale at the tarn. Either go around the tarn on the boggy bridleway, or turn left before the tarn on some nice singletrack past a derelict house, and pick up the bridleway (really only a sheep track) on the opposite hillside. The downhill (on what is according to the maps a bridleway, but very narrow) through upper Miterdale is one of the best in the Lakes, very exposed, and just a narrow track. Stay right when you come near a fence, over a Meadow and down to the only house/farm in Miterdale. A few hundred yards after riding through that farm, stay right onto the small bridleway to sample the best bridleways/tracks of Miterdale forest, and head for the road once you had enough. Takes two hours, if you want more, head over Irton Fell into Wasdale, and climb back up to Burnmoor Tarn from Wasdale head.