One of the main stoic approaches to living a good life is negative visualization. It’s a way to prepare for the undesirable situations that may happen in the future. Positive thinking is often encouraged in the society today. However, by having expectations only for happy outcome is unrealistic. You just set yourself up for disappointments.
Some negative thinking is not pessimistic but realistic. The things you own will likely break or get lost. Mean people will act unkindly toward you. The project you are working on might fail. You may find yourself in a serious illness or injury. The people you love will die. These are just natural occurences. It’s silly to think bad things won’t happen to you. If you have pondered these thoughts in advance you will be able to handle the events more wisely.
Use negativity as immunity.