How do you successfully vivid Daydream?

I really wanna know how to "vivid daydream", I don't know if that's the exact phrase for it but I remember 2 summers back I was able to. I was just lying on my bed staring at the cieling and then all of a sudden my vision blurred and it was like I was lucid dreaming but I didn't fall asleep nor was I in REM. The daydream was like a dream except I was able to remember everything and detail seemed really clear but since it happened spontaneously I was shocked and I snapped out of it. SInce then I haven't been able to daydream that vivid, does anyone know how to do this or have you had any similar experience?