I plan to add some recommended exercises to this site in the near future but until I do here is a really good and and well explained exercise to do before you train, or just during the day. The point is that it improves balance and proprioception in three dimensions. Three dimensional proprioception is critical since although our knees and ankles move most significantly in the anterior posterior plane we need strength, and more importantly quick automatic pretensioning reactions, in other planes in order to prevent knee and ankle sprains and strains. For those whose knees tend to drop inward when running, cycling or working out, this is also great since this will help you body build up appropriate strength, get used to firing the right muscles at the right time and understand where your limbs are in space in order to start to correct or limit that issue. This exercise will work a surprising range of muscles quite hard. We've talked about muscles around the knees and ankles but think about what is going on at the pelvis also.
No more spoilers, read Steve's blog and watch the video. It's not as easy as it looks, so take Steve's advice and perhaps try it holding onto a chair first.