Our emotional mind will harness the rational mind to its purposes, for our feelings and reactions-- rationalizations-- justifying them in terms of the present moment, without realizing the influence of our emotional memory.
There are some surprising payoffs with only a few minutes' practice, like eliminating the loss of concentration that multitasking usually brings. Short daily mindfulness practice in beginners also improves memory, to the point that a group of students who volunteered for a study got significantly better scores on their graduate school entrance exams.
One of the leading theories of why electroconvulsive therapy is effective for most severe depressions is that it causes a loss of short-term memory - patients feel better because they can't remember why they were sad.