If one of you takes a jab at the other during this three-week period, you'll jab back. You're both infused with a new, slightly aggressive energy, and neither one of you feels like backing down from conflict. For this reason, you could get into a doozie of an argument during this phase, unless you're careful to be nice to your sweetie and keep things light and fun.
Remember the Golden Rule: If you don't want them taking shots at you, you're not allowed to poke at them either. On a more positive note, this should be a really fun phase, especially if you stay active as a couple. You've got plenty of energy to burn, so you should get outside together -- go for a walk or, better yet, a run, and work up a real sweat. Team sports would also be a great stress-reliever now; play on the same team for the best results. Neither one of you is satisfied with humdrum dates, like dinner and a movie; you both want something more interesting, unique, dynamic. So use your imagination when you get together, and think up something really fun and different to do. Skydiving, maybe? Racing go-carts around a track? Riding a roller coaster together? Whatever you do, keep it exciting!