It's a uniformed branch, similar to how the military services are run...which means it has similar criteria for health and physical fitness. In fact its benefits are nearly identical to those of an officer/enlisted person in the armed forces.
They don't list Licensed Mental Health Counselors as one of the positions they hire, but sometimes you can fit in under "Health Services." I'm going to look into it because I had originally planned on a career in the Air Force. This looks really, really cool.
Yeah, they do have medical standards like all of the services but some can be waived. You have to talk to their recruiting people to see what can and cannot be.
One of the links I provided was specifically for UPHS mental health professionals - the UPHS is now going to support DOD with counseling services and that significantly expands demand for that particular specialty - and may make them more likely to offer a medical condition waiver - and maybe even tuition reimbursement and other benefits if you sign a contract while still a student.
UPHS is a very small organization that is under the Office of the Surgeon General, itself part of the Office Of Public Health and Science of the U.S. Department of Health and Human Services.
http://www.surgeongeneral.gov/
http://www.hhs.gov/ophs/ (includes a listing of other reporting agencies, such as Regional Health Administrators, another possible employer -
http://www.hhs.gov/ophs/rha/index.html )
I think they have only about 6,500 medical professionals in all. Not many people know of them, but they do some really cool things. They often are in civilian clothes on the job, but you will have snazzy Navy type dress uniforms for formal occasions. Not a bad gig at all.
Some graduate level intern job ideas -
http://www.usphs.gov/student/
http://nhsc.bhpr.hrsa.gov/
http://www.usajobs.opm.gov/students.asp
http://www.studentjobs.gov/