I feel very nervous too, during exams period so I let myself eat something that I really want like a croissant.
I don't love fruits and veggies and before going to have an exam it's difficult for me even to eat a proper meal (cos of stress) so I choose something that I know it's not healthy but I prefer it instead of going without eating a thing. But I do it with moderation and I adjust my nutrition so I won't overdo it. The days that I don't have exams I stick to my plan. My goal during exams period is not to gain, I find losing very difficult so I treat it like maintenance period.
And I'm Greek too, so I guess you have exams at university this period, I'm in the middle of my exams too so I know the feeling!
(Kali epitixia!!! =Good luck in Greek)