My charge was to defend 192 square feet of air.

A three-star hotel in San Francisco offers that size room for $128 a night, though soccer players are more familiar with that number as the space contained by a 24-foot-by-8 foot goal.

For my weekly exercise in humility — otherwise known as this edition of Put Me In, Coach — I played goalkeeper to John Chavez’s striker at the Riverside Soccer Complex.

Chavez is a 30-goal scorer each of the past two seasons for LeBlond, earning first-team, all-state honors as a senior, and will play for Cloud County (Kan.) Community College in the fall.

For my part, soccer was my first organized sport at age 5. I played competitively one more time — in sixth grade — when I ruined my team’s chance for an undefeated season by giving up four second-half goals in our only loss.

One-hundred, ninety-two square feet was far too much room for me to cover then, and more than 13 years later, that remains true. On a dewy and humid morning last week, LeBlond coach Ken Girard started me off with a 5-minute goaltending tutorial, and then it was sink or save.

Essentially, the idiot’s guide to goalkeeping goes something like this: Keep your hands in a W shape when catching shots above your chest. If you try to catch it like a basketball, the soccer ball often will squirt out.

Scoop low shots into your chest. Keep your hands at your sides. It’s quicker to raise them than try to get them close to the ground. Stay in an athletic stance; come out to cut off angles; drop to one knee to corral shots on the ground and push off the opposite leg when diving. Stepping toward the shot slows you down and reduces your range.

The first six are all easy enough to abide by and come pretty natural. The last, not so much. It just goes against my nature not to step toward the ball – especially when you have just a fraction of a second to react. And even as Chavez started lofting soft shots in on goal from about 25 yards out, I couldn’t help but step and push off with the wrong leg. So much for coachability.

We then progressed to some game situations — breakaways, one-touch crosses and then penalties. I quickly figured out you’re going to look pretty foolish if you don’t go all out. Even doing warm-ups, there were a couple shots that looked simple enough, and after a nonchalant effort, I was picking the ball out of the back of the net when it fooled me or slipped through my hands. If you don’t like grass stains, goalkeeper probably isn’t for you.

But effort alone couldn’t save me – especially on breakaways. I charged out, dove at the ball, tried to cut down the angle and watched the ball sail past me just about every time.

At one point I thought I could clear the ball, only to whiff and have John tap it in. In the back of my head, I could her a Scottish-accented commentator saying, “Oh, nightmare for Cooper. What on earth was he thinking, going for a stroll?”

And of course penalties — taken from 12 yards out — torment even the world’s best keepers. I can empathize.

I just felt slow, like my feet couldn’t react to my mind. I guessed right about two-thirds of the time, which even though I’m not an accomplished mathematician, seemed better than average. I could fake one way and get John to shoot the other. I watched his plant foot and approach for a hint.

But the body couldn’t translate those successes into saves. As a result, I lost faith in my ability to react and just started moving early, not a real successful formula against a two-time, 30-goal scorer. Chavez told me afterward he thought I guessed too quickly, but I doubt simply reacting would’ve turned out much better.

He ended up winning the penalty kick competition 4-1. On my kicks, a power approach sent the ball over the bar and accuracy provided plenty of time for a save.

Cleats and goalie gloves would’ve helped significantly. The ground was wet; therefore the ball was wet — both of which made even straight-forward saves a little tricky. But a goal half the size probably would’ve been my best defense.