Any suggestions for a book about practicing Gratitude or Mindfulness?

I’m looking for a non fiction book about practicing gratitude or mindfulness (or both!) in my day to day life that preferably doesn’t have heavy religious undertones as I find that I do not relate to them, as a non-religious person. If you have a recommendation that does include religion/religious subject matter, I will still probably check it out but it isn’t exactly what I’m looking for.