I was lucky - didn't have any time of as an NQT, only had one cold last year and that was just after OFSTED so I think the stress didn;t help. I swear by Sainsburys REVIVE. It is a fizzy multivitamin and I take it every morning. That said, I was a TA before my NQT year and also did GTP. I had a week off during my GTP year with a violent sickness bug that took some getting over, but my mentor and three other teachers and a third of the kids were also off in the space of three weeks with that one!