Joy In Every Circumstance?

This Conference, I heard that it's possible to have joy in every circumstance because our joy comes not from the circumstances of our lives but from the focus of our lives, which is, or at least should be, Jesus Christ. This confuses me a bit. How is it possible to have joy in every moment of our lives, even the monotonous or tragic moments? I understand that having an eternal perspective can minimize one's negative feelings about their current circumstances and help them look forward to the joy they'll experience hereafter, but it's hard to feel joyful when I'm doing math homework or when things are going wrong. Maybe I'm confusing the concept of joy with some other feeling. Maybe I'm not focussed enough on the Savior. But it seems to me that not everything about life is joyful, and that a person would have to have a strong eternal perspective to be able to look past the tedium and tragedies of this life and look forward with joy to the life to come. I don't know whether I need to adjust my focus or whether I need to try to become content despite the hardships of life, but as far as I'm concerned, joy is pretty hard to come by. I'm not sure how one could have joy in every circumstance.