On motivation in the lab

Without going into too much detail about the state that our lab is in due to the economy and sequestration, there is a great lack in motivation in some people in the lab. This is not new, as I have written about this before, but it does make me wonder what PIs do to motivate people in their lab. How do you make sure people stay enthusiastic about doing experiments and if they’re not, how do you try to help them? Personally, I find that it helps to associate with people that are working hard and are trying to be productive rather than to hang with the people that seem to have given up hope to get experiments done and papers written. But other than that, when I am in the position to mentor someone (like an undergrad, summer student or tech) I find it hard to find a balance between giving someone the freedom to schedule their experiments and plan their time for them for example. How do you go about motivating the people in your lab? Or do you feel that’s not necessary as people should come with enough intrinsic motivation?