How to run some code in Unity3D after every x seconds?

How to run some code in Unity3D after every x seconds?

I need to execute a code every x seconds till a condition is met in
Unity3D C#. The code should run irrespective of other code as long as the
condition is true and stop otherwise. As soon as the condition turns
false, it should stop executing and run again if condition becomes true
(counting no. of seconds from 0 again if possible). How to do that?