By noon I was exhausted. How do these positive people do it' They must shop a lot. If you don't think about spending money, buying stuff is an excellent distraction.

I was looking forward to dinner that evening with my girl friends, but that was eight hours away, and since I'd taken the day off work I didn't know what to do with myself. When I'm not working, my free time is spent thinking about how I should be working. Or doing chores and sleeping. Or, more precisely, doing chores, quitting chores and sleeping. None of which sounded like a festive birthday option.

But I was torn. I knew I'd feel good if I got through some of these chores, like taxes, expenses, laundry and bills. I've been putting them off and here was a chance for self-improvement. Then it hit me: there was another opportunity for self-improvement: I could go shopping! For make-up.

"For what?" Joanna asked, shocked. I repeated: for make-up. "But you don't wear make-up." That was the point. It was time to look into it. Why not buy some foundation? I needed to shake things up a bit.

Sephora is a department store for cosmetics, and the women who work there seem to wear every product they sell. They also have a hands-free headset - the kind air-traffic controllers wear when landing planes. They patrol around the store with serious expressions, asking things like: "Do we have Bliss body butter in stock?" Then they'll wait, without moving, until they get a response. "Negative." Got it. Who are they talking to? The make-up command centre? If these women were working the security at Heathrow, we'd all feel a lot safer.

Wandering along the anti-ageing aisle, I looked like a lost lamb. When the Sephora lady approached, I told her it was my birthday and I was interested in buying a cover-up or a lotion or something. The 'or something' is where I went wrong. As she began a monologue about the benefits of a specific cream that comes in a crystal bottle, I cut her off. "Does that come in a tube?" She looked horrified.

I explained that I travel and need something more durable. When she showed me a jar filled with loose powder, she opened it and I sneezed. "Does that come in a compact?" I asked. She shook her head. "It would compromise the integrity of the minerals in the powder if it were pressed." I nodded. Who knew powder had integrity?

One by one, item by item, I began.

to get more depressed. There was a wrinkle cream called Shar Pei. How is seeing that every morning supposed to boost confidence? Finally, she found me a product I could relate to: When Hope Is Not Enough. It's a serum that comes in a little brown bottle with a dropper, so it even looked medicinal.

After all the time I'd put in, I had to make a purchase. But I'm done with self-improvement. The more I tried, the worse I felt.