Sometimes I'll just say outloud - "Thank God". Or "God Help Me get through this today!". Formalities are not necessary. I just close my eyes quickly and pray in my mind sometimes sitting in front of this computer. It's what you emote (internally or vocally), think and feel that matter, not whether or you're on your knees next to an alter.
My prayers are never formal - usually seconds in length, filled with the desires and needs that I feel need to be addressed at the time.