The skill sets you develop by overcoming and embracing challenges, adversity, and struggle. These are the best assets because they allow you to excel in the arena of life. When you develop and master them all the fun material things come your way.
There is a laundry list but they are not material things they are skill sets you can develop like confidence, resilience, self worth, love, persistence, active listening, mindsight, and far more. Think of them as an investment portfolio well diversified. The cool part is these assets allow you to perform in the arena of life at a very high level. All the material things come to you as a result.