The Teessiders are sitting second on the Championship table following the weekend’s 1-0 win at Crystal Palace and although they have made an unbeaten start to the season (five wins, two draws), McDonald knows Premiership promotion is still a long way away.
“Not excited at it at all at the moment. Just got to take it one game at a time,” McDonald told BBC Sport.
“We're delighted, we want to keep this unbeaten run going. But there's a lot of games to go.”
McDonald also said that he has to work extra hard at the moment to keep an ongoing hamstring injury at bay.
“I have to be now it's re-occurring. This time it was the left one, at the end of last season it was the right one,” he added.
“It's about managing it a little bit better, especially when we've got midweek games in between the weekend ones.
“In both cases, it's been in the third game of a week I've broken down, so we need to manage it better.”