I am training for my first marathon in October (aim 2h55m). My PBs are 37m 10k and 1h20m HM. I do 100 km a week with two hard workouts. What should be my easy running pace? I am always in doubt my 4:20/4:30 min/k comfortable for my cardio may be too fast for my bones and joints. What do you use to do? I also train in trails.