1. Being too fat - no-one gives a shit
2. Being too poor - you have 4 months to save
3. Living too far away - as long as you are not (2) above then this is no excuse (and NO not even on environmental grounds, sorry, this is exempt)
4. Being shy - well you are NEVER going to get over being shy unless you try are you?? Look upon it as aversion therapy (but cheaper)
5. Being pregnant - I seem to remember an 8 month pg Thomcat shimmying her stuff a couple of years ago quite happily. There are chairs and loos and we are in the middle of London so if you do go into labour there are hospitals nearby. It is not an excuse.