Learn to sweat in peace

Sometime ago I read this in a book:

"The harder you are on yourself, the easier life is on you. Or, as they say in the Navy Seals, the more you sweat in peacetime, the less you bleed in war."

Actually, I thought about it when I ran some days ago the Gutenberg Marathon in Mainz/Germany. There is that one bridge which you have to cross twice and pretty late in the marathon. Last year I failed their but for this year I had some "hill training" nearby my work in the Taunus. Hill training in the way that the whole run consisted of a lot of ascending slopes especially also when the run was nearly finished (i.e. after 90-120 minutes). This really gave me a boost on race day when I was just right before the bridge at the deepest point of the whole course.