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

How bad do you want to live? Of course you fight for your life. Running is NOT a good thing. Tells the Predator your prey and they will be more prone to attack you then.The sign has it right be as intimidating as possible. A 6' staff and a large knife will help but a firearm is best. You could also take a small axe but only use it when the cat is charging you. Just don't miss. Swing fast, hard and use short strokes. As many as possible till it runs off. Maybe a cattle prod. I'm sure the cat wouldn't know what hit it with a prod but being so close...well maybe that's not such a good idea...lol. You'd probably only get one chance but it's better than not having it. Another possible solution...change where you run, go to a safer area if possible. As far as snakes go leave them alone and they will leave you alone. a 3 or 4' forked stick to pin them down with worked wonders when I was a kid and hunting snakes. If you pin it down behind the head you can pick it up (as long as you get a hold of it right behind the head) then toss the sucker a good distance away from you.