I celebrated the descent into the second half of a century quite appropriately by developing debilitating back spasms last week. Jodi, the health center nurse practitioner, told me that it wouldn’t have taken a great strain to send my back over the edge. Indeed, the spasms began about six hours after I’d vacuumed and replaced a chair mat. And my mother didn’t believe that housework was bad for the health. I know better now.

Since last Wednesday, I’ve woken up, rolled out of bed in the approved way, and felt the spasms kick in immediately. I get it. My back doesn’t tolerate standing. Walking and sitting are all right most of the time, but my back doesn’t take to waiting for buses, stopping to admire museum or other exhibits, or washing dishes (yes, the old-fashioned way). I’m guessing vacuuming is on the same list, although I’m going to to have do a manual override on that preference. Life goes on, just not without pain that remains undaunted by prescription ibuprofen and muscle relaxant.

On this day I met JT at Lincoln Park Zoo, where we were treated to an insider’s view of the Nature Boardwalk, from native flowers and other plants to fish and birds. I would have loved every moment except for the acute, nonstop protest from my lumbar region against the slow pace and the stops to smell the roses (really, to admire the cone flower and other wildflowers). By lunch time, I was ready for a prolonged sit down.

Just before we started the walk, we’d observed a trumpeter swan pursue and peck at a tiny family of tiny ducklings. One even went under to escape the wrath of swan.

If you haven’t seen the boardwalk yet, I encourage you to add it to your walking list. While it’s still scraggly in its youth, it’s quite lovely, and if you’re careful and observant you’ll catch native beauties like the purple cone flower and eerie, otherworldly sounds like the call of what we think is a least bittern hidden under all the foliage. To the impatient jogger who gave us a brusque warning as she flew by — maybe you should worry less about your physique and more about your spiritual well-being and social skills. Are you surprised enough to be annoyed when people are casually strolling the Nature Boardwalk? Did you notice It’s not called the Nature Jogging Path? But shouldn’t complain. I’m glad that I don’t work with you and your Type A self-importance.

After lunch on the Patio at Cafe Brauer, my back finally decided to relax a bit (unlike the jogger), so we visited the gorillas, three of whom had ventured outside on this pleasant, overcast, slightly cool day. After a while, they all headed in. Perhaps they had heard something.

At the Brach Primate House, baby white-cheeked gibbon Sai demonstrated his increasing independence, leaving Burma’s clutch to practice his swinging skills. She’s more willing to let him go now, even ignoring him while she focused on grooming Caruso.

Remember “The Lion Sleeps Tonight”? They also sleep during the day. They are also more advanced in years than I am, so they’re entitled to their cat naps.

The European white stork was huddled in the nest, which it’s close to outgrowing. Human children who are said to “grow up so fast” have nothing on most birds, including storks.

In the McCormick Bird House, the black-winged stilts appear to be nesting. The tawny frogmouths look like they haven’t moved since January. The snowy egret fluffed his handsome plumes as he took care of an itch. In the free-flight area, we saw some newcomers, including a pheasant and a pheasant pigeon. I was reminded of the pygmy goose that is really a duck.

At Regenstein African Journey, Maggie the West African dwarf crocodile was out of the water, although with her back turned to her admirers. A pygmy hippo was soaking in the water, at one point displaying an impressive set of teeth. A visitor thought it was a baby. The pygmy doesn’t get the air time on cable that its larger relative does.

And so to RJ Grunts for the tuna trio and a shake.

Not a bad birthday at all.