What jumped out at me with that "I must explore this further" spark was this:
"She has clients distinguish productive worries (which spark action) from destructive ones (which trigger an endless loop of catastrophic thinking)."
I have a friend who's favorite phrase is "Worry is just an invitation to trouble". He's talking about the destructive type of worry, of course. The endless loop of catastrophic thinking not only distracts you from enjoyment of the present, but can actually be self-fulfilling. People tend to return attitudes, in that they avoid lonely people, are hostile towards angry people, but seek out the company of the happy. Worrying constantly about being alone can invite that situation to continue.
The productive type of worry is something I've never thought about in such terms. I'm used to considering all "worry" to be destructive or stressful, but the worry about my job is motivating me to take classes and/or certifications to make me more employable. It's also motivating me to take on extra tasks at work (like offering computer training to my co-workers) to become more valuable to my current employer and expand my resume.
The problem itself (employment uncertainty) could spark either type of worry, of course. I could spend all my time obsessing over scenarios of bankruptcy and fall into that destructive loop. Wait, I sometimes do that anyway! No worry is entirely one or the other, just as no problem worth worrying over is ever simple.
So, as Pollyanna as it sounds, whether a worry is destructive or constructive really is up to you. It may take work and vigilance to turn a destructive loop into constructive action, but it's possible.