I still dont understand if wanting to do something bad, shows you have a bad heart or not... I just dont know...
That part, actually doesn't matter.
And here's why:
On an instinctual level, as a species of animals on this planet, of course we want to do moralistically bad things. That's human nature. All humans are like that. MOST men, are homicidal. Why do you think there are more men going to prison all of the time for violent crimes? It's because that is our hunter instinct. And obviously, the men that don't go to prison, don't act upon that natural instinct because of the consequences for doing so.
So, it doesn't matter what you want to do in life, it matters what you do and do not do in life.
It is more beneficial to NOT act upon our basic, primordial instincts, than it is for us TO act on our basic primordial instincts, because of the consequences for doing so.
What makes it that way is the Social Constructionism of Civilization.
See? Morality doesn't have to enter the equation, it can shape itself accordingly.
HOWEVER, BECAUSE it can shape itself accordingly, that's also how you get people that really don't seem to understand the severity of the consequences for their actions for trying to game the system.
Best example I can think of in that situation, is the long history of the Catholic Church and the sexual abuse of minors. Or, also, King Henry VIII:
Preaches human morality until everyone goes home, Cardinal retires and then sexually abuses the minors used within the church community when nobody is looking. Consequence is a Hell of a political mess, potential loss of position, imprisonment, or execution.
King Henry VIII:
Wanted a Son, kept having Daughters. Abused his power and had the women executed for infidelities they did not commit. Once this was discovered, the consequence for doing so was that the man was executed exactly the same way he executed his women.
Came into autocratic rule due to his tactical and innovative approach. Let his ego get to his head and believed himself to have become a God, and was literally murdered by his own council as famously foreshadowed by the Ides of March as a consequence for his arrogance.
So for a tactical approach, I would suggest instead of actively trying to gain advantage, since often doing so results in the unfortunate disadvantage later, becoming comfortable with a disadvantage and calmly waiting around for someone looking to gain an advantage from your disadvantage, might actually be the better approach. It takes the work out of it for you, and simultaneously flips the script to your favor. Why go hunting, when you can harvest what food you can get from around you agriculturally, and set up traps and wait for the food to come to you instead? Whenever you begin to run low on what is around you, just pack up and move to another location where there are more resources in abundance for you to use.
Is it limiting in the short term? Yes.
But does it benefit for the greater long-term of surviving? Also yes.
It's actually a developmental skill for humans, to think this way. Part of why I love dragonflies so much is that they hunt through interpretative movement, like a football game, actually. Rather than chasing the food, a dragonfly will land nearby, watch the pattern of its prey, and then go to where it algorithmically expects to show up based upon that movement. Similarly to how football/soccer players try to interpret where the ball is going to go, BEFORE it gets there, so that they can just be there ahead of time and wait for it to show up. Surprisingly, dragonflies have something like a +92% hunting accuracy rate this way, meaning that they are masters of interpretation. That is not innate to us like it is them however, we have to teach ourselves to think like that, with their species, it's as instinctual to them as it is for us to chase our resources directly, rather than indirectly.
So when it comes to morality, I'm kind of like:
What about it? It'll shape itself.