The head chef proudly came to our table and declared that he had caught the lobster himself.

We use the emphatic reflexive pronoun himself here to stress that the chef did it personally, without anyone else's help. (Note: "hisself" is grammatically incorrect!)

Unfortunately, while trying to show off his culinary skills, he then proceeded to accidentally burn himself with the flambé torch.

We use the reflexive pronoun himself because the subject (he) and the object of the verb (burn) are the same person.