Who gives this purpose to our lives? Our self or something else? It's relevant because it answers how you reached your conclusion.
Haven't you ever wondered about why it's just that rule-breaking that makes us horny? Doing the forbidden. We're basically just another type of monkey, (primate) and no other monkeys in nature have rules about what kind of sex is acceptable, (Bonobos fuck anything and everybody at any time and in any way). If we take a look at nature, having any rules at all regarding sex, besides consuality is perverse. We are the most perverse animal on the planet, and we on this forum, the so called perverts are following our urges more than any other humans making us, in my humble opinion the least perverted, (ie in conflict with natures design). But then again we're part of nature so I guess anything we do is actually natural and non-perverse, so never mind that.
My point is that there is no right and wrong. All the rules about what is are social constructs most often with very superficial use. Humans aparently love having rules to follow, or we wouldn't have any. And we also love breaking our own rules.
A perfect example was the explosion of Arab music samples in US hip-hop after 9-11. I'm not saying hip-hop is evil or perverse. Islam is in the Western mind forbidden today so it becomes extra exciting no matter how much we try to deny it, (We tend to connect Arabs with Islam even though most muslims aren't Arab). And the records have aparently been selling, so the tactic works.
Following your desires, ie doing things that make you happy I couldn't possibly see anything wrong with. Giving in to lust I wouldn't say is mindlessly following anything. It's denying lust which is mindlessly following the social constructs that any thinking person should see through. Just because most people don't, doesn't make it good, natural, right or non-perverse.
When it comes to sex I don't think any of us are free from the rules that where hammered in at an early age. Either we mindlesly follow them, or we purposefully break them. But free, non of us are.