prove that the order of H is greater than 1 (it implies that H≠{e})

Question

Let {G,∗} be a group with identity e and let a∈G be a fixed element in G with a≠e. Define H={x|x∈G and x∗a=a∗x}

(1)prove that the order of H is greater than 1 (it implies that H≠{e})