Ordinary days also have their own quiet happiness.
Tips
memory
平 (flat/level) + 淡 (bland/diluted) = flat and bland, either literally for taste or figuratively for life/style.
usage
平淡 can be neutral or slightly negative. Compare with 平凡 (píngfán, ordinary but neutral) and 无聊 (wúliáo, boring). 平淡无奇 (píngdàn wúqí) = utterly unremarkable.