C# add helth over time

This is a snip it from my current shield health and what I am trying to figure out how to do is add heath back to curShieldHealth over 10 seconds. In that 10 second period I would like the curShieldHelth to get back to 100.

 public int shieldHealthMax = 100;
 public int curShieldHealth = 100;
 
     
     
     void Update () 
     {
         
         if(curShieldHealth == 0)
         {
             
         }
         
     }