My baby is crawling everywhere - how do u mums manage to be vigilant at all times and Ensure baby does not do something harmful?

There is no way other than to baby proof your house and supervise him closely. Things that can be toppled over or small things that he can swallow needs to be put out of reach. But the best way is just follow them closely. My gal loves to play with doors and peeking behind them. Once I was slow in following behind her, she accidentally open the door but her the other hand was still on the floor . Cried like mad. Another way is to put her in an exersaucer , Play yard or playpen when you need to run off to do chores