By making it impossible for them to receive health insurance when they leave active service.
Why is it that the majority of Democrats can't stand the military?
Update: Here's more on this issue. It seems that the Obama administration could care less about the US government's stated obligation to take care of Veterans who have service related injuries or illnesses. The US government's responsibility to providing medical care for service is a vital part of an enlistment contract, and this will surely cause hangups in recruiting despite the increase in VA funding.
On the other hand, the problems within the deplorable medical insurance for those on active service - known as Tricare - isn't very well known. You would think that those who enlist would ask about that, but they never seem to.