However, if you only have the occasional no show, don't panic. It could be your body's way of showing you that you're not in the right space to have sex - or just be one of life's annoying inconveniences. A respectful partner won't judge you harshly - though may need reassurance that you find them attractive.
Many men assume that the longer sex lasts, the better it is. In reality, it's about quality not quantity. Rather than thinking of unsexy things to last as long as possible, get your lover warmed up beforehand and let yourself go during sex.