I've been contemplating Abraham Maslow's Pyramid of Human Needs a lot lately. He actually called it "the hierarchy of needs," but I like the words Pyramid and Human more; better branding. In any event, it's a really handy idea to have in your toolbox, one of those semi-obvious insights into human nature that's easy to miss, or forget, but never gets old.
Basically, you start at the bottom with your fundamental *Physiological needs*, starting with the need to breathe, because if you can't breathe or eat or perform certain biological functions, those things more or less take over your existence. That's the bottom line, and most of us first-worlders have it covered, thank goodness. Direct manipulation through the withholding of food and water is rare in our lives.
After that you climb up to the level of *Safety*. If you don't have a sense of security about yourself and the things you consider yours, be they material, familial, or whatever -- if you're _afraid_ -- you're stuck with that, and you really can't go much further as a human being. Safety is a psychological concept of course (real security is impossible; you can't control rocks in space that might fall on your head or wipe out your species) but it's important for this concept to make its way into your mind, however that happens for you.
For most of us, being in debt, especially "bad debt," can stick us at this level. Sickness definitely pegs us here. Also, this is arguably the level on which a lot of politics operates; overt fear-mongering, appeals to anxieties about "them," the specter of ruin, apocalypse, etc. Unfortunately, when an appeal to this psychological level works, it's very potent.
Assuming you're able to rise above the chains of fear, uncertainty and doubt, you reach the level of *Social needs*, summarized as: