watch her, and maybe run beside her on the treadmill. Or go to use the same equiptment at the same time, and let her have it. Or ask her how to do a stretch the right way or how many reps she does. Or simply make a comment when you are by her.
OR you could do something totally embarrassing when...
Get a friend to come with you! I find that it is way easier to actually work out because you have someone there with you. It's like you are obligated to work hard. You can also try imitating what other people are doing. Or scope out someone in the room you want to impress, and work hard to make...
You can find some at a pet store in liquid form for all of these. The strips are fairly accurate for the nitrate and ammonia, but not so much for the pH or other things. Liquid is best for accuracy though. A company called Hagen makes some that are relatively cheap and come with enough testing...