Ok, I'm less than an hour into learning TypeScript

Question

The following code works, however, I feel it's less than elegant. I added the drink() function.

 

How to improve it? Thanks.

interface Person {
    age: number,
    name: string,
    say(): string
  //  drink(): string
}

let mike = {
    age: 15,
    name:"Mike",
    drink: function() {
          if (this.age < 18) {
            return ("Sorry, you're too young to drink.");
          }
        else {
            return ("You are old enough to drink.");
            }
     }
     say: function() {
            return "My name is " + this.name +
               " and I'm " + this.age + " years old!"
    }
}

function sayIt(person: Person) {
    return person.say();
    //return person.drink();
}

function drinkIt(person: Person) {
    return person.drink();
}

console.log(sayIt(mike),drinkIt(mike));