One day a leopard saw a gorgeous deer grazing within the sun. The leopard was hungry and wanted to hunt the deer for a meal. "That deer looks delicious. I will be able to quietly go near it and attack! the deer wouldn't even know what struck it," The leopard thought. On the opposite side, the deer was chewing on fresh, green grass. "This grass is so sweet. I should be coming here every day. the flowers have such sweet nectar, the grass is so supple" Thought the deer. Suddenly, in the open land, from a distance the deer could see the leopard slowly crawling towards it. Instantly the deer leapt and ran for its life. The leopard chased the deer. "I must run faster!" Exclaimed the deer, and put all its concentration on putting distance from the leopard. The leopard, which was not such fast a runner, and had underestimated the deer, soon saw the deer disappearing out of sight. 
Never be over confident of the things you can do. 