Car tires come with limited amount of rubber for traction and friction to keep the car from slipping. The more the car drives the more that rubber wears off. The limit is when it becomes dangerous when tires are smooth. Dangerous enough for the tires to explode.

Likewise, our mental health needs regular maintenance. If we keep using it constantly without maintenance the resistance or rather resiliance gets weaker and the explosion would be the burn out and disfunctionality. A nail puncture after another in parallel to a stressful event after another will lead to deflation which means we are still functional but it needs 10x the effort to produce the same result as a healthy person or a new tire.