YSK: a foam roller costs about the same (or less) as going out for lunch, lasts for ages, and can instantly make a huge difference in all kinds of muscle soreness, back pain, etc.
from /r/YouShouldKnow
YSK：一个泡沫滚轮的成本和出去吃午饭的成本差不多（或更低），持续时间长，而且可以瞬间让各种肌肉酸痛、背痛等问题得到巨大改善。