Start making your own happiness a priority. Your needs matter. If you don't value yourself, look out for yourself, and stick up for yourself, you're sabotaging yourself. Remember, it IS possible to take care of your own needs while simultaneously caring for those around you. And once your needs are met, you will likely be far more capable of helping those who need you most.
I've been told something similar to this before and it's always gone against what I've been raised to do. Look out for the others, help everyone else, put your needs on the back burner (and keep doing so until they aren't even on the stove anymore). And, it's quite likely that we have all been told similar things throughout our lives.
Me? I've been taking fifteen minutes each morning to spin yarn, knit, write in my journal, or just listen to some music. It's a good way to start the morning and reminds me that I am important, too.