What is a one-sentence summary of the following article?
If you feel less than excited about having a little "benefits" time with your FWB when they suggest it, take a step back and examine your own reaction. Figure out why the idea doesn't appeal to you at the moment. Of course, the reason might be pretty obvious (like, you just took a tumble off of your bike and your body hurts all over), but if not, ask yourself: "Am I upset with my FWB over something they did?" "Am I distracted by all the stuff I have to do for school or work or anything else?" "Am I just too exhausted to hook up right now?" Once you've figured out exactly why you're not feeling up to it, share it with them. Whether it's because they've upset you or it's due to something else entirely, be honest with them. Keeping them in the dark could hurt their feelings and make them resentful, so keep your friendship alive and healthy by letting them know the score. For example: "I want to keep hooking up, but if we're going to, you have to know that you hurt my feelings when you did/said __." "I'm sorry, but I have to finish these projects for school/work/etc. before I can play." "I'd love to hook up right now, but I'm too zonked out to be any fun." Soften your "no" with a promise of things to come. Offer other options to assure them that this isn't a blanket rejection. Show them that you're still interested in maintaining your "benefits" status even though you're not up for it this very second by either making concrete plans for later or offering them a reward for their patience, like: "I can't right now, but let's definitely get together this weekend." "Maybe I'll call you once I've finished all this work, and we can talk dirty." "I don't know when I'll be free, but maybe I'll make it worth the wait and we can try something new."

Summary:
Ask yourself why you're not into it. Tell your FWB the reason why. Give them an alternative.