When our cat lays down on her side and is in the mood for belly rub, she does this kneading motion in the air while purring loudly and rubbing her head into all

When our cat lays down on her side and is in the mood for belly rub, she does this kneading motion in the air while purring loudly and rubbing her head into all nearby objects, so for simplicity we just assume she's happy :) But on the other hand, sometimes a cat is going somewhere and unintentionally steps onto a blanket or something soft, then just starts kneading like it walked into a quicksand and it's face is like "goddamn here we go again"