I'm sure you've seen all the "fitspo" memes/t-shirts/quotes about strong being the new skinny/healthy/black...but I'm here to tell you that strong is the new nothing. Being strong (physically, mentally, or emotionally) should not be downplayed by comparing it to something else.
Physical strength is measurable, mental strength is harder to quantify, but either way, why do we keep trying to explain strength as something else? Saying that strong is the new skinny or sexy seems to downplay it, like it's not ok for women to be strong. I'm here to tell you that it is both ok and desireable for a woman to be strong. If that displeases the people in your life...get new people who appreciate you for who you are!
If you want to get stronger (not skinnier or sexier), then do it! Get physically strong by exercising your body. I mean, let's face it, we could all probably use some more exercise, right? To get mentally strong start with some positive thinking. You'll be surprised how far that might get you. I'm an eternal pessimist but I've learned to make the best of most situations I find myself in.