I suggest you read this awesome post by Mo Bitar or don't if it's not something you were gonna do anyhow. I think the article was really neat, however I also think there are times when you are just being social and going with the flow to go for a walk or have some coffee with your friends. Once I felt like the walk, but not the coffee so I just walked with my friends, but didn't do the coffee. I was surprised how "offended" my friends were that I didn't buy the coffee and just did the walk, but ...