So I’ve been reading about Einstein and learning quite a bit about his theories. I really had no idea what relativity meant. In college I knew a physics major who would say: ” Attitude check: I hate this place…Relative attitude check: My mother hates this place.”
I also had a physics class in college and even read Aristotle’s work on physics in grad school. Been a long time.
So I had been thinking on the concepts of inertia and momentum metaphorically. But I had to look them up to be sure.

INERTIA

(dictionary.com): the property of matter by which t retains its state of rest or its velocity along a straight line so long as it is not acted upon by an external force.

Also known as Newton’s first law of physics. I’m more use to hearing this definition though: An object at rest stays at rest, unless an external, unbalance force acts on it. The original was in latin, so I suppose it’s open to interpretation as to the exact words. But the meaning is fairly clear though. Metaphorically, let’s apply it to fitness:

A person on a couch watching TV will continue doing so unless something convinces him to get off his butt and exercise.

AND
A person who works out regularly will continue to do so until something makes him want to stop.
It’s pretty hard to break a habit, whether it is good or bad.

MOMENTUM

It’s the idea that applied Force = mass x acceleration. So you can be smaller and faster, or bigger and slower and have the same impact. Metaphorically people talk about gaining or gathering momentum. Building a bigger impact generally by gathering more people to a purpose. So the faster you go, the harder it is to stop, and the bigger you are, the harder it is to stop. Another way momentum is sometimes used is in terms of being hard to stop: “I’ve got momentum in my studies, I’m learning more every day. Nothing can stop me now!” So this just adds to the idea that once you start exercising, it’s easier to progress and less easy to stop.

FRICTION

Friction acts against these things. Some of the metaphorical friction I’ve experienced in my fitness life are getting busy at work, injuries, sickness, or other kinds of stress.

MOTION

These are all concepts and laws of motion. Motion is important to longevity. Basically, the more you move, the longer you live. The fewer injuries you have, the better you feel, etc. If you are in good health and able-bodied, you are fortunate. You have the capacity for a lot of motion. And you should keep as active as you can. The MOMENTUM you gain will make things easier as you face FRICTION in the future.