Health zone heals player but I have a problem

Hello I am creating a special health zone that gives the player health and my current scripts health is going up super fast and I want it to go up by 2 hp per second. How would I do this?

Here is the health zone script.

{     public PlayerHealth playerHealth;     public float healthGain = 2f;          void OnTriggerStay2D(Collider2D other)     {         if (playerHealth.currentHealth < playerHealth.maxHealth)         {             playerHealth.currentHealth += (int)healthGain;             playerHealth.healthBar.SetHealth(playerHealth.currentHealth);         }          if (playerHealth.currentHealth >= playerHealth.maxHealth)         {             playerHealth.currentHealth = playerHealth.maxHealth;             playerHealth.healthBar.SetHealth(playerHealth.currentHealth);         }     } }