Almost anyone who has spent any time in Europe or in the US military in recent years finds that if you just stop trying to play with conversion formulae and let your intuitions learn what 20 degrees feels like and how long it takes to drive a kilometer, within a few DAYS it becomes as natural as the obsolete English systems with which we're still encumbered in the USA. If you stop fighting it, it'll be instinctive before you realize it, because the metric system really is more intuitive than English units. We learned metrics when I was in grade school (late '40s, early '50s) but it didn't mean anything to me, either, until I just lived it!