If you are over 40, then your brows are probably over plucked, thin and sparse.
Eye brows are very important, they frame your eyes and give your makeup more of a polished look. I also think that very thin eyebrows can be a bit aging and this is just my opinion. If you like your eyebrows thin then that is fine with me.
Brows are all the rage these days just look at Instagram. There is so many eyebrow products out there; pencils, gels, pomades and powders. I like to use two different colours of pencil (the one with very fine tip) lighter at the front of my brow and a darker one on the tail of my brow and then I set them with a brow gel.
It does not matter which product you use, this more about the technique, so use brow products that you feel most comfortable with.