Try something small, a little ritual, to "center" yourself. When I'm at home and being apart from him is a little too overwhelming, I like to get into a calming position (for me, it's prostrated on the floor, as though I can pretend to kiss his feet). My Master also wrote me what we cutely call my "slave prayer," just a small mantra of things that he finds important and wants to emphasize in my life and wants me to remember. I say it at work when I can't talk to him, or if he's out and won't be home for hours... It's just a way to keep yourself calm and centered in his absence, and it doesn't have to be minutes and hours long, just something small to say "this is who I am, this is who I serve, now pick it up and keep it moving, kid" whenever you're reminded of the distance/absence.