These are the martyrs who are a mess inside and out but put others before their own healing, their own progress.
Think about it. You’re available 24/7 for friends and family while ignoring and overextending yourself.
And what state are we in after all that?
Tired, stressed and frustrated. 
You’re no good to anyone like that. You can’t perform at your best with these emotions in the way.
You must care for number one, first.
I don’t care how you interpret it if you're not on top form yourself how can you effectively help anyone else. If I have a hope of contributing I need to be in a good place first. If I’m not, all I’m doing is hurting the people around me.
How do you get into that frame of mind if all your life you’ve been told being selfish is a bad thing?
Simple.
The best way to prove or disprove it to yourself is by experiencing the results.
Experimentation.
How do you do that?
Let's give yourself a week of self-love. Set some boundaries. You will do these things first and foremost before any demands are made of you from, friends, family or work.
Try this everyday for a week:
    * 
Meditate/ Make Quiet Time
    * 
Eat Healthily
    * 
Exercise
    * 
Read/Learn
    * 
Set Goals
    * 
Show Gratitude
 
How do you feel now?
Make time to fill up in whatever way makes you feel good. Take the opportunity to care for yourself, and your goals only then can you wholeheartedly care for others.