How do I defend myself against a full grown Mountain Lion...?

the sign had it right. hold your ground, act big, be loud. and you should never ever try run away from a predator. first because they're faster than you, second because it's a predator and it's an instinct for them to chase things that run. this is why they most often attack bikers and runners. if you need to get away, do it slowly and keeps your eyes on the animal. more importantly though, you need stay aware of your surroundings because cougars are ambush predators. odds are that you won't see it beforehand if a healthy one wants to attack you. that's really all you need to know about attack prevention. if things get more serious, a knife could help (something you can get out quickly, a swiss army knife isn't going to cut it) i recommend a fixed blade knife in an easily accessible sheath, maybe even bear mace. as for the rattlesnakes, saving a little recreational time isn't worth risking a lethal bite, give them their space and wait or find a way around them.