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：一個泡沫滾輪的成本和出去喫午飯的成本差不多（或更低），持續時間長，而且可以瞬間讓各種肌肉痠痛、背痛等問題得到巨大改善。