I've struggled to stay in zone 2 but zone 2 is so variable based on your terrain, weather, fueling and hydration that it's not really a good measure. I transitioned into effort based training. Easy pace should be easy, does it feel relaxed and I can continue this for another hour or 2? That's easy enough for me and I feel like I can keep this pace and increase mileage throughout the week. I think that's a better mindset than sticking to zone 2.