The knee tendonitis is probably due to a variety of things. Age - I am 34. Lack of attention to recovery - With two very young children I have been not getting enough sleep and also not paying enough attention to things such as icing, foam rolling and stretching which I used to do far more strictly. And the real killer - doing dumb stuff like jumping on hard surfaces too much and not warming up enough. I have been having autologous blood injections to treat it (they take blood out of your arm and inject it directly into the tendon). This has been helping although I am still a long way from resuming full activities such as actually playing basketball.
I wish I could post some nice photos of my gym. Currently I am operating out of a temporary facility whilst my house is being built. That will be great as I will have a huge space to train people right downstairs that would put some of the gyms on MTV's cribs to shame. My equipment list isn't that crazy though because I don't train large groups of people. Usually a maximum of 2 at a time. When the new house is finished I have a few plans to change that but for now i consists of the basics (a power rack, barbell, lots of weights, a variety of cardio machines which I mostly only let people do high intensity sprints on. I feel bad about charging people good money to watch them ride a bike for 30 minutes), plus a few special toys (various specialty bars such as SS Bar, Trap bar, a bunch of kettlebells, a bunch of bands, the vibration plate, a GHR, various sandbags, several weight vests, a weight sled, gymnastic rings, a landmine etc).
The mental training side of things you mention is interesting stuff. So hard to quantify or test though. But psyching up definitely works so there is something to it.
Cheers
Jack