Athletics is a skill representing physical training in any practice intensive physical feat, such as a parkour, running training, climbing, swimming and so on. The higher the skill, the more experienced and capable an individual is to leap nimbly from roof to roof without dying in a spectacularly hilarious fashion that makes for an amusing anecdote.
0: You might not drown, or routinely fall off things, or be a complete invalid, but your lack of training is mighty noticeable when you try.
1: Basic physical training, meaning someone probably references it way more than they should.
2: They have a routine. Oh no, they want to tell you about their routine.
3: The person with a story about how they survived a boating accident and swam to shore.
4: And saved someone else while doing it.
5: By repeatedly going back and forth from shore until they saved everyone drowning.
6: After being starved and having no sleep for a week.