You can be surprisingly accurate by pacing off 10 steps at your natural gait, and then measuing this. Doing this a few times will give you an average for a natural step for you. Most people are under a yard per step at a normal walking pace. You will find that every 10 steps is 9 yards or 8 yards, etc...

You can use this method to find distances anywhere and be fairly close in your estimate. It's good to do this and inclines to get your pace on different grades.