Although Ralston usually prepares himself before setting out on his adventures, what event(s) occur(s) at Havasupai that shows Ralston does not always look before he leaps?

At Havasupai, Ralston jumps fully clothed into the main river where the current is much faster and colder. Ralston nearly drowns. Ralston falls into a cactus bed after trying to cross over them on a slippery ledge. Knowing his sandals are improper footwear for the job, he still attempts the maneuver anyway.