Humans are great at forgetting the past and not acting in their best interest for the long term future. But we are great at acting in our short term, or immediate best interest.
While the survival principle holds for all decisions we make, it is skewed dependant upon many variables. And one of the largest is based in time.
Our tendency to focus upon the immediate future and present, ensures our physical survival is generally well looked after. But it takes much greater presence of mind to see how our values and beliefs can be upheld, and even enhance our long term emotional survival.
The other interesting thing to note, is that once a particular survival threat is removed, you are free to work on those longer term ones. But any event, can cause a diversion in attention, and we resort back to looking at our present or short term future.
Stress is often a cause, due to its impact being felt like a more imminent physical threat, hence demanding our urgent attention. Modern stressful events aren’t normally deserving of our immediate attention, but evolution hasn’t quite removed that from our biology just yet. As such we resort to many odd coping strategies such as eating to avoid stressful emotions, due to our biology thinking it is actually an imminent physical threat.