We've all received the well-meaning advice to "stay positive." The greater the challenge, the more this glass-half-full wisdom can come across as Pollyannaish and unrealistic. It's hard to find the motivation to focus on the positive when positivity seems like nothing more than wishful thinking.
The real obstacle to positivity is that our brains are hardwired to look for and focus on threats. This survival mechanism served humankind well back when we were hunters and gatherers, living each day with the very real threat of being killed by someone or something in our immediate surroundings.
That was eons ago. Today, this mechanism breeds pessimism and negativity through the mind's tendency to wander until it finds a threat. These "threats" magnify the perceived likelihood that things are going — and/or are going to go — poorly. When the threat is real and lurking in the bushes down the path, this mechanism serves you well. When the threat is imagined and you spend two months convinced the project you're working on is going to flop, this mechanism leaves you with a soured view of reality that wreaks havoc in your life.
Maintaining positivity is a daily challenge that requires focus and attention. You must be intentional about staying positive if you're going to overcome the brain's tendency to focus on threats. It won't happen by accident.