It’s sunny. 70 degrees. I’m in San Francisco. Nike’s flown me out for this weekend’s “Global Running Summit” and, while I’m here, I’m signed up to run the half in the Nike Women’s Marathon, just a week after finishing my first marathon. After yesterday’s exuberant run in Chicago, I’m starting to think, should I try and do the full marathon again this weekend? Once I start thinking that way, it can be trouble.

Running in San Francisco’s a whole ‘nother deal than Chicago. I step out of my hotel downtown and see a hill across the street. Of course I want to run up it. Halfway up, sanity returns for a second—I just did a marathon Sunday, and I’m racing Sunday and I don’t EVER run hills. What if my muscles react in such a way I can’t run Sunday? I turn off the hill and follow what seems to be a flat course. Then I turn toward “home”—my hotel—and have little choice about course, since a wayward run and I’m lost. Look at this: I have to ascend Nob Hill whether I like it or not. Epic. Soon I discover that running down a steep hill is a challenge of another kind.

Providence has intervened. I’m sticking to the half on Sunday.