I brood and feel it's productive.

My reaction is similar to your clients. I’ve had depressive tendencies, which I definitely don’t enjoy, but I sense it’s not the same thing? 

Intriguing though as I think someone close to me might be like this. Or at least at this border, while still falling into depressive tendencies. Their likely placements are Scorpio rising, Sun/Saturn, Cap moon.

Just read through the comments and understand the discussion better, though I don’t think I’ve ever thought to enjoy it in the moment or put myself there intentionally. I can definitely see how it’s productive.

My first thought was Scorpio moon, as a potential brooding placement. Mars involvement, sublimation of the drive (finding satisfaction) through thought processing. 

Brooding, ruminating, rehashing, working through the same issues but with added perspectives, or new puzzles as they occur.  I do it but I don't enjoy it, just can't avoid it.  I've even said to myself, in that inner dialogue, "Not now, get back to that later." 

Seems inevitable as we age.  The fresh, distracting, shiny-object opportunities no longer appear or appeal.  

You phrased it so perfectly! I'm both a saturn and capricorn dominant despite being a libran (I have a stellium in libra actually), I have moon in taurus and taurus is my second strongest sign, I have a capricorn stellium (including saturn) in the 5th house so I tend do define what's fun for me a tad differently than most people. And last but not least cancer is my third strongest sign so dwelling on past hurts and occurrences is a huge thing for me