Is it normal to fantasize too much

i constantly fantisize about all different things and find myself wanting to make some of them come true. Some are about me and other men , me and couples , me cross dressing and many more . i also have alot of sex with myself pretending i am the girl or the guy . I am in a relationship and have a good sex life .Am i allone out there or is this more common than i think.Thanks for listening..