How much sex is too much sex?!

Okay..so..hubby n I have been together forever in a life time (almost 18 yrs). He is a straight horn dog to say the least. He LOVES sex (positions, don't get me started). When we were younger we would have so much sex it would hurt..lol. Now that we are getting "older" and work ALOT, he still wants it at least 4+ times a day. Don't get me wrong, I love sex but damn. When he wakes up, when we get home from work and before we go to sleep..am I being ridiculous, or should I just suck it up and enjoy it while it lasts..?(Hell we aren't getting any younger😂)