Andrew Huberman· PhD
For me, that can include some hills, and when I say hills, they could be very steep hills, but I simply slow my pace down in order to stay in that roughly zone two range. Or it could be that they are more low grade hills and I might just slow down a little bit or I might even push myself a tiny bit that day. But really I'm just trying to build that long endurance. I'm trying to build up my capacity or maintain my capacity to go a long distance without fatiguing.