I REALLY react to the hormone changes, so I can usually tell with fair accuracy when I am ovulating without the kits (although they could be useful to confirm!) based on my sex drive. If I can't focus on anything else than attacking LP at night...well...that is my night to get pregnant. Nature is full of trickery like that.
Changes in mucus also occur, and LP says it feels different and more appealing to him when I am ovulating as well.