You're just having a bad physical luck day. There's different kinds of luck you can get per day (item, physical, friendship/relationship, money), and you can either be having a good day or a bad day. If you use a Lovely Phone or see Katrina, you can find out your lucky item for the day to help the tripping. Sometimes it'll be a specific item or a more general category, like official-themed pants. The bad luck will be gone tomorrow, though. Until then, watch out for bees (they're faster on bad physical luck days), jellyfish (ditto on them), and walk to avoid tripping (don't carry any balloons or coffee if you do run!).