According to Osho, mindfulness is sustained by total absorption in the present act: let the current task be the figure and everything else recede to the background. Drop the idea of 'trivial'—every small act is a hologram of the whole, thus sacred. Continuously shift attention with circumstances: driving, just drive; eating, just eat. Then the flow of meditative joy becomes naturally constant.
Do one thing at a time with your whole attention, treating every small task as important.