But how do you waive a magic wand and make 60,000 more soldiers join the Army and 12,000 more Marines join the USMC? Recruitment for those branches is trying really hard as it is, but there are limits to what they can do. Does he plan on bumping soldier pay (yay! but unlikely), reduce physical standards, ease background checks, or introduce conscription?
You lower recruiting standards to allow more waivers for criminal offenses, lower ASVAB scores, reduce the number of medically disqualifying conditions, etc.
The result is, as you would expect, a generally greater expense per-soldier due to having to deal with the expenses accrued by higher training failure rates, larger numbers of soldiers being discharged due to chronic medical conditions, disciplinary problems, or court martial proceedings, and a resulting hit to morale and professionalism.
There was a lot of it during the early part of Bush's administration to try and support the "churn" introduced by the wars, and it wasn't particularly pretty.