How can I become cold and carefree again?

[Anonymous]

I was very cold-hearted, brutal, and careless, I 'd easily put myself or my ego above anything and anyone no matter what without feeling any remorse. I enjoyed being alone and unemotional... But over the years, after being in a few relationships and losing some family members, I've changed and I started caring a lot more, feeling sorry for others, I gave up on many of my old traits and I basically feel like it negatively affected me and made me weak. Now I've become soft and people can use me easily and cause me a lot of pain.
So, for those of you who managed to turn this around and became stone-hearted after having enough of people bs, how do I find my old self and identify? As my life was a lot more enjoyable and pain-free back then?

[Blackcosmo]

What you need to learn is the art of saying no sometimes. Being a cold person isn't a good thing and what's good is that you have changed. Those traits are what make you a good person so you don't want to lose them. If you're a good person you can still say no and you won't be used. Show people you have boundaries.

[Guy13]

It is in the Bible... Pharoah in Egypt where God hardened P heart as P harden his own heart. Book of Exodus, Moses, Plagues, and Pharoah.

[MountAverage]

Or maybe stop trying to bullshit yourself.