how much exercise is considered too much?

I have a question regarding what is too much exercise.

I have had an insane amount of energy lately..and try to compensate by eating 2600-3000 calories a day. I literally get on an elliptical machine and go with no effort for 90minutes straight. I also do a 20 minute yoga video with some back exercises light stretching. This I am able to do daily and it doesn't even wipe me out!

what is the deal is this too much? where is all this energy coming from???

Not saying this is you, but I see people at my gym all the time going like hell on an elliptical machine for ages and you think to yourself, "holy cow, look at her go"...until you realize she isn't even sweating and then you walk by and see her adjusting the intensity of the machine and it's at 1 or 2 or 3...lol. 

Do you measure your heart rate when you do the elliptical?  What range is it in?  What level of resistance are you at?   If you are at high resistance and a heart rate of around 150 for the whole 90 minutes, then you ought to be training for the Olympic Marathon...lol.  If not, turn up the juice on the machine to get you into that range...

No I actually have not measured my heartrate, I don't really know how to do that other than when I put my hands on the metal parts of the handles that check it.  For at 24 year old that exercises daily what should my targe range be?  The resistance is at 10-11 for me from a 1-18 range. I used to be at a 5-8 resistance range.

I've always had a naturally low bp and heart rate though, bp being about 90/60 and a heart rate range from about 50-60bpm.