According to the Merriam-Webster dictionary, the simple definition of "therapy" is the treatment of physical or mental illnesses.
That's a simple definition with a broad range of possible options, from a course of antibiotic therapy, physical therapy or psychotherapy.
My therapy often involves bikes; sometimes riding them, sometimes working on them.
Wiping down a frame, lubing a chain, checking spoke tension... these tasks can give the hands something to do while the mind sorts out life's challenges. I've got some friends that feel the same way, and my basement shop is the spot to hang out and talk, have a beer, and eliminate disc brake rub. The bike stand is like a psychiatrist's couch, and maybe grease stains on a rag could be used for rorschach tests.
However it's interpreted, it's enough to have a place to go and an activity to do to help put things into perspective. Life will always give you things to ponder--good and bad, and between my bikes and my wife's bikes, there is always a bike that could use some love, even if it's just a shiny coat of bike lust.
Which does make me think... maybe my friends are coming over just to get free tune-ups and bike cleaning... I'll have to go throw a bike in the stand and contemplate this.