This video shows you how to internalize triplets in a simple way.
Set your metronome to 60 bpm and tap the quarter notes with your hands as given by the click. Consciously try to feel the beat with your whole body, as if you had to drop your entire weight on each click. Then switch your tapping to eighth notes (two eighths for every quarter). Next, move on to eighth-note triplets (three even taps instead of two per quarter).