A Lightworker is someone who has worked through most of their personal issues and because of that moved from the (lower) ego into their Heart.
Personal issues are usually inner child issues, things from our (early) childhood that often got enhanced later on in life until someone sorts them.
This can be a gradual process, can even take many lifetimes, but it can also be a more conscious decision to solve the problems because you want to feel better and happier.
As you clear out the closet, work through issues, you get more and more ready to move into the Heart. It's quite self-explanatory that you cannot live from the Heart, be open, have an open Heart, when you are still plagued by insecurity, low self-esteem, trust issues and so on.
So in order to get into a vibration of love, in the Heart, you first have to clear out and work through most of your issues.
The more you do that and get into your Heart the more you are shifting into being a Lightworker.
A Lightworker is someone who has an open Heart, lives in and from the Heart and with that a natural longing rises to serve. Serve the planet and people. This is not the 3D serving that comes with a "what do I get back for that?" thought. It's a 5D serving that comes straight from the Heart when the giving and serving IS the receiving. But that's not why you do it. You do it because it is Love, you are Love.
When you're in the Heart space, can open the Heart fully or close to, the backdoor of the Heart opens. You can physically feel this, it can be a little jolt under the shoulder blade (usually only the first time).
Then, through the open backdoor, the Light & Love of God, Source, The Divine comes in, moves through your Heart and shines out the front.
This is accompanied by the sound "Ohm" and "I AM". I AM being your Monad vibration, way way way above your Higher Self, the part of you that is as close to The Divine as you can get.
This Light fills your body and all its cells so you radiate it. It can also heal ailments as these cannot exist in this high vibration.
When you got this most of the time, let's say 80-85% of the time, you are a Lightworker as then the Light of Source shines through you and from you.
In this state of Love & Light you cannot not give, serve, love, share. There is no selfishness in this state of being, only love.
None of this takes real efforting, although going through the stage of resolving issues isn't always pleasant. But none of this can be forced by the will. It is a process for which you have to be ready, even the sorting of issues.
You cannot decide with willpower "I will not hurt anymore" or "I am happy & joyful now". It doesn't work that way. It's a process for which you have to be ready.
You can of course help it along so it goes faster.
This also means that in essence everyone is a Lightworker, but not everyone is as far as described above so the Light isn't shining through them yet. Some will get there this lifetime, others maybe the next one. It takes as long as it takes to get there. It's not a race or contest.
The only thing that matters is that you are where you are, and that's okay. Everyone is exactly where they're supposed to be.
I hope this resonates, is tangible, as there are so many misconceptions on what being a Lightworker comprises.