Begin a doctor involves doing a huge (very) of different things. You May be involved in the (treat) of colds, or giving (inject) diseases, some of which are very serious.
It's Hard to remain uninvoled when you know thata patient's (recover) is in your hands.
If you are a (surgery), you have to deal with even a greater responsible because it really can be a matter of life and death when you are performing an (operate).