Explanation: If you would have said we decided to hike the canyon by themselves. Then you would be talking about some one else because you are using the word "them" But It clearly says (We) But when it comes to the word ourselves the begining "our" means us and us is like we. Thats the best way I could put it .
The sentence "My friends and I lazed around all morning" has a negative connotation to it since "laze" implies laziness. However, "My friends and I relaxed all morning" means the same without the negative connotation.
