I lost my student deferment in 1969 when I quit college after one year. At that time (before the lottery) I knew I would be drafted and soon was ordered to undergo a "pre-induction" physical, which I easily passed. I was determined not to be drafted (as an immature, self-centered and spoiled baby-boomer, I was more afraid of DI's than combat itself - think Pvt. Pyle in Full Metal Jacket). I had heard that there were shrinks in Boston that would certify one as mentally unfit, so I hitched up there and enrolled in group-therapy sessions after being certified as paranoid (ha!) and delusional. I knew the important thing was documentation, but I was determined to use any means necessary including going to jail, as I figured civilian jail would be better than military.
Fortunately for me, they came up with the lottery system in 1970, and I returned to normal life, albeit with a large and permanent chip on my shoulder towards involuntary servitude. I did not and do not see any reason for the War but I didn't really care about it as long as I was not involved directly. Obviously, this selfishness is not something that a good father would promote in his children, but I feel that the social contract is nullified if society allows what is in effect slavery. I do support a strong military and think the answer to manpower problems is better pay, period. If they would have fewer unnecessary wars, it would also be helpful.
The tricky part of getting a mental deferment is being convincing without actually going nuts. I'm not sure that I was completely successful; I maybe somewhat paranoid and even delusional, but compared to some vets I've known I'm Dr. Phil. Also, I don't really know what metric would be used in determining unsuitability; if one was really psychotic, one might make an excellent soldier, for all I know. However, society has become much more attentive to individual problems than in my day, although the army is still going to take whatever it can get and round off the square pegs as necessary. There's also the whole issue of sexuality. I say that I would have done anything to avoid service, but in fact I did not check the homosexual tendencies box out of actual fear that they might make me prove it somehow. Like Dick Cheney, I had better things to do...
The bottom line is every kid (but especially boys) should have a long and well-documented medical impairment of some sort, mental or physical that would preclude military service. This is long-standing practice; I remember how everyone of the doomed on the bus back from Richmond felt about the loud-mouth college boy waving his TB x-ray around. I turned out to be lucky in the lottery, but if they're really after grunts, luck won't cut it. If they restart the draft, resistance will build quickly, but each individual needs to have a personal resistance plan in reserve. Again, I'm not saying that military service is evil in itself, and for some guys, maybe most, it can be a good thing, but for some it is devastating. These guys need to plan ahead, and a parent can help.
I'm sure they will try to resurrect the draft, probably under a "national service" rubric to which I still object. Involuntary servitude is slavery, before and after the 13th amendment, despite what courts may hold.