If you're more external, you tend to find a greater sense of meaning, purpose, and fulfillment from interactions with others.

If you're more internal, you tend to find a greater sense of meaning, purpose, and fulfillment from within.

When it comes to working out, external people tend to be more motivated in a group setting. They also tend to be more motivated by competition (e.g., they're more motivated to train for an organized race than to just train for the sake of it).

Internal people don't need as much of those elements to feel motivated (e.g., they can find adquate motivation to just be bigger, stronger, faster, or thinner, etc. than they were yesterday, even when no competition with others is involved).

Both have inherent strengths and weaknesses. External people are more inclined to go out of their way to help others. They're natural leaders who tend to enjoy organizational involvement and frequently find fulfillment in volunteer work (e.g., in a community or religious setting). But they can also be more likely to be into conspicuous consumption, compete vicariously through their kids, and put other people down (in an effort to elevate themselves). Relative position in society (or within an organization) is a big deal to them. For example, they'd be at least somewhat excited about a job promotion with a more impressive sounding title, even if the pay was the same.

Internal people, on the other hand, tend to be more wrapped up in their own little world. Along those lines, they're more inclined to keep to themselves and have a relatively live and let live attitude (their version of the Golden Rule is more or less, "don't bug me and I won't bug you"). Relative position in society (or within an organization) is almost meaningless to them. To them, a job promotion with a more impressive sounding title but no more pay is basically worthless (and, would, in fact, be viewed as a negative if it involved more work, stress, or responsibility).

External people tend to most enjoy doing things that necessarily involve others (e.g., competitions, social events, etc.). Internal people, on the other hand, tend to most enjoy doing things that may, but do not necessarily involve others (e.g., going on a walk, watching a movie, etc.).

External people also tend to be more communal whereas internal people tend to be more private.

People talk about extroverts and introverts, but I think external and internal (even though the root word is the same) are more comprehensive and more throughly describe what makes people tick. And, again, this is a spectrum and not binary.