My goodness, how old are you? No getting a desease means using a condom each and everytime you have intercourse. This protects both of you. As far as weakness goes, if you are feeling weak, you will sleep. Period. That's the body taking care of it's self. You can't overwork a machine if it takes a rest on you. The old saying is "If it feels good, do it." If your tired, go to sleep. If you both want more, go for it. What else can I say?