Some people are against wearing a heart rate monitor while they workout because they feel it would be annoying to wear the strap around your lower chest. While I feel zero discomfort whatsoever wearing my strap, you may want to try going strap free.
The NuMetrex Heart Rate Monitoring Sports Bra ($49.50) works with the Polar WearLink Transmitter and compatible watches. It also connects with most fitness machines like spinning bikes and elliptical trainers with integrated monitoring devices.
The NuMetrex Heart Rate Monitor Sports Bra gives you the power of a heart rate monitor with the freedom of strap-free wear. Buy one on Numatrex.com.
Not sure what your target heart rate is? Check out the Fit Calculator to find out!