But, what's so unnatural?
If we follow the "restrictions" set by the Church, we in fact, live how we ought to.
Fasting is healthy for us. There's no better diet than vegetarian. However, the Church allows us non-fasting, as well. So, it's bonus.
Not fooling around, is also healthier than fooling around. When one is in a committed relationship (aka marriage) than each partner is "safer"...both physically (less chance of contracting any kind of disease) and mentally/spiritually (less likely to be hurt by the other partner).
No addictions allowed. That's great! When someone is addicted to something, any thing....they are not themselves. They crave only that one thing. So, not being an alcoholic, drug addict, constant gamer, magazine reader, etc., is in fact, healthy - and natural.
Giving up our vices isn't easy. However, once we make an effort, it gets easier....and in truth, we are so much happier and healthier as a result.