In Survive It, medals are awarded due to how far down the run you make it. If you make it to the bottom, you get to start at the top and do it again.
While this can be done on any run, I would recommend Mount Robson in the Rockies. Furthermore, it would be good practice if you already had:
The Tree Hugger achievement in SSX worth 75 pointsSurvive Trees Deadly Descent without equipping armor (in World Tour) A gold medal on Mount Robson is two complete runs down the mountain, followed by a small fraction of a third run. As mentioned above, if you can make it down once without armor, managing it twice with armor is much more doable. Take it carefully, there's no need for Tricky or boosting since your biggest enemy is the trees.
Starting on your second run, the lower half of the mountain gets covered in snow and it's difficult to see. Stay calm, and remember that when it happens, you're likely about to run into a pattern of three fallen trees to quickly jump over.
EDIT: From Calex dEUS, using a low level board helps, as it goes slower; some runs, going faster will simply ruin you. Additionally, using the
button to jump as opposed to the right stick is easier.