Nothing Borrowed, Nothing Lent

As we move into the Christian season of lent, it raises an interesting question. During lent, Christians live a more modest lifestyle giving up particular pleasures. Other religions also set aside times where certain physical needs are left unmet to create an experience of want. Muslims have Ramadan where for a month they do not eat at all during the day and Jews have Passover where for a week they give up any food that does not give you constipation. The idea behind it seems to be that you can't appreciate the air condition unless you spend time in the heat. Abstinence makes the heart grow fonder.

My question is, is that true? Do we really need to lose something, or at least do without it, to appreciate it? If we were thoughtful enough, could we appreciate what we have while still having it? Does life give you a lens such that the normal becomes invisible and you have to put yourself in unusual circumstances to focus on it?