I'm 81 Years Old. I Just Had A Physical By

I'm 81 years old. I just had a Physical by my Family doctor with Complete blood work. I exercise
4 x times a week for ( cardio. ) and 2 x times with weights ( 12-15 reps with light to moderate
weight ) My Blood work came back with good results for my age. However, my ??? to you is
that I'm Very very tired / no Energy. I get plenty of Sleep ( good sleep ) 9-11 hrs. per night. I do
not No why I'm so tired/no energy. PLEASE HELP
P.S. Do I need to see an Specialist who sees older people like me ???