[SerializeField]
private int maxHealth = 100;

private int health;

void Awake()
{
    health = maxHealth;
}

public void TakeDamage(int damage)
{
    health -= damage;

    health =
        Mathf.Max(
            health,
            0
        );

    if (health <= 0)
    {
        Die();
    }
}

public void Heal(int amount)
{
    health += amount;

    health =
        Mathf.Min(
            health,
            maxHealth
        );
}