The purpose of the target heart rate is?
a) to measure how much you improve.
b.)to see if your exercise frequency is enough.
c.)to see if your workout is long enough.
d.)to see if you are exercising hard enough.

I'm pretty sure the answer is

B.) To see if your exercise frequency is enough

you may having too much sleep.. a good night sleep consists of about 7 hours. more than that could be the reason you're still tired throughout the day.

yes because there are aliens