Why do we have to wait eight months until we're born but we have to wait 12 months until my birthday?

Because we develop inside our mother's uterus for 8 months.

After development, we are given birth and that will mark the day of our existence in the earth. So every 12 months, or a year, we celebrate that moment. :)

the more fit you are, the faster the recovery. your heart rate drops most sharply in the first minute after you stop exercising; it should then fall about 20 beats a minute—a drop of less than 12 beats a minute is considered abnormal. this “recovery heart rate” is measured as part of an exercise stress test.

i believe it is true.