I am fully against war, in almost all its forms. Even a so-called "defensive" war would be hard for me to get behind. War sucks, and we'd all do better to have less of them.
Enter the classic idea (and still excellent) of sending the warmongers to war. It's just common sense. If you advocate for an aggressive war, you must participate in it. If you think you are too old, then you need to rethink your hawkish stance for you will still be compelled to fight. That's real "skin in the game" as they say. At risk of sounding as political as I am at heart, the Bush administration has many a hawk that never spent time fighting war, yet they are the most excited to wage it. This would end if there was a mandate to fight wars that one advocates.