How to create a question that loops until it receives correct answer?

How do I create a program that repeatedly asks the question until the user gives the correct answer? Below is a simple code to explain what exactly I'm asking...

    prompt = 'What age is Seán? ';
    age = (input(prompt));

      ageans = 21;

      if age == ageans
          disp('Correct!');
      else
          disp('Wrong');
      end

So if someone were to answer 37, rather than 21, how would I change the code so that it would loop back to the original question to ask the user again?

Answer 1

[Adam]

age = 0;
ageans = 21;

while age ~= ageans

     prompta = 'What age is Seán? ';

     age = (input(prompta));
     if age == ageans
        disp('Correct!');
     else
        disp('Wrong');
     end 
end

[Seán Ó Héir]

Thanks Adam! Worked perfectly