I became interested more in this fruit when I would notice both an energy boost and a general feeling of happiness. This most likely can be explained by the larger amount of vitamins and minerals found in it. I encourage you to research on your own what these are, as I am finding many things I'm not familiar with.
Some of the commonly listed health benefits would be: Helping with proper digestion, urinary tract infection's, flu-fighting, lowers cholesterol, and providing a defense against some types of cancer. So adding a few slices of grapefruit to a breakfast meal or having some juice with dinner may help you feel more up to par.
I've personally noticed it helping in recovery from work-outs and/or high-stress environments. The taste is quite bitter, but it is growing on me over time. If you really can't stand it, try mixing it with apple or grape juice . So yes I would have to say grapefruit is a great fruit!
Sites I learned most of this from: