Here you should discuss a stressful situation that you were able to overcome and keep a positive tone, do not say you never came across a stressful situation. Typical answers can be:

Our team's targets were increased three fold and initially everyone was overwhelmed by the number, but we discussed it with our manager and he was co-operative and understood the situation. But he wanted us to give it a try and was ready to reduce the targets to a more realistic number.

You can also talk about a very demanding project where you worked for long hours/2 shifts and had to sacrifice on family time, but once the project was done you got recognition for the hard work and you were over the stress.