1. "Never borrow money for a depreciating asset." Dave Ramsey (and others)
Tamara Keel said it slightly better: "Never pay money to lose money." The basic concept is that, if you can't pay cash for something, you can't afford it. The only thing that approaches an exception to this is real estate; and, even there, not all real estate is created equal when it comes to appreciating/depreciating in value. If the interest rate you are paying on the loan is not less than that rate at which the property is appreciating, you are losing money.
2. "Be where your feet are." Dr. Kevin Elko
I had a chance to hear Dr. Elko speak recently, and he is a very engaging speaker. The essence of his advice here is to not let your mind be distant or distracted. This is something I've struggled with for years as my mind has a tendency to wander down rabbit trails. It vexes The Queen something fierce. Cell phones, iPads/tablets, social media, and epidemic levels of "ADHD" only make this problem worse.
3. "If you chose not to decide, you still have made a choice." Rush - "Free Will"
Indecision is nothing more than making the unconscious decision to allow circumstances to make your choices for you.