Not far at all ... many are tenants of very strung out staff members who are working at least two "wog" jobs in addition to their terribly serious and important cult posts. The exhaustion and distress is contagious, any form of BT exercise is just not going to happen.
Sea org BT's are also absolutely twatted 24/7 due to stress, regular all nighters and the constant thought of that billion year contract that they're stuck with, until their equally knackered landlord manages to do a runner. Severe embarrassment due to being trapped in the SO also makes them horribly lethargic and apparently many feel obliged to stay where they are to try and support their host who's forced to wear a silly sailor suit and pretend to be happy and enlightened all the time. That is very painful and upsetting to the average BT.
Public cult BT's are slightly more relaxed and sometimes even able to jump a few centimetres on a good day, but are usually so confused and introverted due to absorbing the endless hubbard indoctrination and harassment by the aforementioned cult members that they rarely bother to try ... unless to attempt escape of course. A non cultic public gathering (ie a normal party) may tempt a few to make the leap, I've heard that a nice, hopefully sane, non scientologist looks very tempting to a cult trapped BT, understandably.
After thinking about it for almost two seconds I can see clearly (no pun intended) that BT's have the best deal really, all they have to do is hang on tight and that can't be too difficult because as we all know there's no amount of tin can grasping and silly question answering that is going to shift them!