Comfort & Complacency are two sides of the same coin.
Nothing in nature gets stronger without stress and challenge. Trees don't put down strong roots without wind and drought. People don't develop character strength and mental resiliency without new challenges that force them to adapt to new situations, learn new skills, or evolve their mental models. The more challenges you come through, the greater your confidence becomes in knowing you can handle anything that comes your way. Embrace challenge like a warrior!