You're right. Human beings are not searching for a local/global maximum, we try to follow the easiest route there is. So, if you really can't motivate yourself

You're right. Human beings are not searching for a local/global maximum, we try to follow the easiest route there is. So, if you really can't motivate yourself, try to find the easiest path there is to get you exercising. One easy way is to make it obligatory (the same way elementary school is obligatory - and for most kids boring). Open your calendar, pick 2 days of the week and add 1/2 hour of exercising there. If you fail to do it, find some 'punishment', like doing over-hours. Play both the role of the student and the teacher. Maybe it will work. Most importantly, start easy. Don't exaggerate or you will never make it a habit.