I sleep for plenty of time but am exhausted in the morning, what can I do about that?

Sleeping for plenty of time might also be sleeping at wrong times. Do you take quick naps in the afternoon?. This could also be a reason why you do not have proper sleep during the night and hence you are exhausted in the morning. Lack of a proper sleep can also be due to some worries that keep your mind awake. Try doing some breathing excersises before going to bed.Medical conditions like thyroidism and cholesterol are also reasons for constant fatigue.

I find that it helps to set an alarm for an hour before I have to wake up. When that alarm goes off, I chill in bed. Don't fall asleep again but don't do anything. I have another alarm for when I have to be up and that is when I get out off bed. Be sure to eat something!

Going to the doctor is certainly a good option, as you might have some sort of sleep disturbance or anything in your mind is not enabling you to rest well despite sleeping plenty of time

You could try adapting your diet to include more vegetables, or fruit. Another aspect is monitoring what kind of sleep you get, if its light sleep or disrupted you will feel tired, you need REM/deep sleep to feel refreshed.

You can make yourself more earlier at night and this way you'll get more necessary sleep and or tire yourself out more so than you don't feel so tired throughout the morning.

You need to make sure that you are not getting too much sleep. Too much sleep can make you feel exhausted in the morning when you wake up. Also, if you take something to help you sleep like Ambien, Melatonin, etc. those can give you a hangover type feeling the next morning making you exhausted. If you need to take something to help you fall asleep and stay asleep then you should make sure that you are not taking the medicine too late at night and also that you are not taking too much of the medication when you take it. Any of these things can and will cause you to feel exhausted in the morning when you wake up.