I've read a lot of Holmes recently, and while I'm not a man, I do think Doyle portrays Holmes' issues in a way that is relatable.
Holmes core thing though is that he has an almost ADHD-esque craving for novelty and tolerance for risk taking. He also can't stand not actively working on things, and when he's not working is when he's depressed. He doesn't seem to know how to actually feel good, but he knows how to be useful, thus his penchant for productivity boosters like cocaine.
He's a great character, but I wouldn't over pathologize him according to today's understanding of mental health. Doyle was a physician and gave Holmes various traits similar to what he had seen in his patients.
Holmes, being an exceptionally observant man, definitely would observe that walks raise the mood, allow for (most often silly) ideas to come and, last but not least, increase observation capabilities, attention to details and speed of thought.
Arthur Conan-Doyle did an extensive walks back then, but his hero was written to not to. This is not right.
As I recall Holmes did in fact do a lot of walking. He vacillated between periods of inactivity(cocaine, violin, shooting V in wall with a revolver) and intense activity (taking up disguises and doing various physical activities including walking all across London and elsewhere.
Just because your logical mind says one thing is good to do and you know you should do it you are not going to always obey your rider, the inertia of the elephant takes over.
So you need a trigger to snap out of it, for Holmes it was a new case.
> and intense activity
AFAIR those had a specific purpose (chasing a perp, tracking down evidence, etc.). Most of his thinking he did sitting in a chair and smoking his pipe for hours on end (sometimes the whole night).
No they are not. He plays violin and shoots a gun inside his house for fun.
Holmes is basically a border collie?
If this is an accurate summary, the character sounds relatable enough that I might try one of these books.