When sex is great with your partner, you would assume that it would always stay that way. However, when times are getting stressful, sex might turn boring, as well, and it will result in a longer time for either you or your partner so become sexually excited, so if you want to have sex, you might need to spend some more time with the foreplay, or you need to have timed sex that is not part of a schedule either.
If you want to go for the easier solution, that is, focusing on the foreplay, then here are a few tips that you can follow. First of all, do not get naked right away. Spend some time with caressing and fondling your partner's body, or even give each other a massage before you would slowly get rid of your clothes. And once you both are naked, resist the temptation to focus on the other's privates first. You should create a relaxed and cozy atmosphere and make both of you forget about your stress factors. This is why enhancing anticipation is the key before oral or manual stimulation of either the clitoris/vagina or the penis. But once you both are almost begging for penetration, you can start concentrating on those privates before the real action would begin.
However, you might only want to have a quickie when you meet your partner. In this case, you need to text him or her a couple of hours before you two would meet. Be specific about what you want to do, but always leave an open question for the sake of anticipation. Try it and you will get back your hot sex life.