It's not about holding onto the joy and peace so tightly you fall apart when they dissipate. It's about being in the wave of joy and peace that you express gratitude for the moment, know this too shall pass.
But even as it passes, it doesn't mean you have to experience the polar opposite. In those lower dips, you can recall this vibration, the vibration of joy and peace and choose that instead of falling into the depths of an overreaction or heaviness.
It's not about avoiding the lower emotions and experiences but making them more manageable and able to sift through easier and quicker (and of course with Grace).