Well, I would have to say sex. First off, there is no limit to the amount of times you can do it each day... so the time issue mentioned earlier is irrelevant. Also, you really show someone you love them through sexual intercourse. (Well some people do, others are just jerks, whores and prostitutes, so sex means nothing to them. If you fall in this category just ignore that point.) Furthermore, isn't the whole point of life to reproduce and pass on your genes to the next generation?
Finally, if you can't ski can't you still snowboard?!?