Reprimanded

I got reprimanded by my boss today. I got the speech on how I am the junior-most mananger in the company and how I have to work up to my potential. Who wants to do that? The issue of me being habitually late was also brought to my attention. I also got reprimanded for not staying late everyday. It's not like I have anything better to do. I just go to the gym after work and then go home but after 5pm rolls around I just want to get the hell out of the office. The feeling actually sinks in at around 3pm.
I have actually fallen asleep during some of our management meetings. It is usually myself and our 68 year old accountant, who end up falling asleep. The problem is that he is old and has an excuse. I on the other hand am only 22. I don't like drinking coffee but for the past couple of meetings I have been bringing some coffee into the meetings just in case I feel sleepy. I haven't reached for it yet.