BE OPTIMISTIC BUT BE PREPARED FOR THE WORST
There are a lot of ups and downs, but you can ride them out if you're prepared for them.
Learning to expect problems saved me from a lot of wasted energy, and will save you from unexpected surprises. It's like our life. The ups and downs are inevitable, so simply prepared for them.
Sometime I ask myself why I want to take on some new, big challenge. A substantial losses always a possibility. Can I handle it if it doesn't go well? Will I be asking myself later " Why did I ever do that?" " What was I thinking?" . I am actually a very cautious person , which is different from being a pessimistic person.
Call it positive thinking with a lot of reality checks.