Whenever get to a point when you're climbing a mountain off set paths and you can't progress forward any longer because the grade is too steep, simply face backwards and start jumping. Just point your butt toward the peak and continually hit the jump button. Also try moving slightly from side-to-side as you try this. You can often snag a rock along the way and shimmy up a mountain without having to use a set path. Sometimes facing forward at a 45-degree angle helps, as well.