What's the meaning?

tschubauer: Not like its hard...jump into water and flail your limbs around. Congratulations, you're treading water!




Lagtastic: It's impossible for you to know how hard it is an adult to learn something like this unless you have lived it. I have tried, I can kind of tread water, but I cannot "swim" well enough to save someone from drowning, or really even prevent myself from drowning.



What does he mean by living it here?



Thanks a million!