I couldn't disagree more with the above. Bodies are different - for mine, exercising without being properly fuelled - with carbs too! - is a catastrophe. It makes me feel absolutely terrible for the rest of the day, and hungry!
Also, morning would be a terrible time for me to exercise. It doesn't really have to be in the morning - the body burns calories in sleep too so it doesn't really matter if you get the metabolism boost during the day or night.
Generally, I think healthy scepticism should be had with the "exercise makes you less depressed" -mantra. I used to believe this and started jogging/running. I was too tired to live, I basically didn't live at all, just run, run, run, dozens of kilometers per week, running from my depression. Eventually I was in great shape and more depressed than ever.
Now with years of therapy and the right medication - I can exercise, and actually enjoy it, and feel it boost my confidence etc. (But not in the mornings for me!)