Hi WR
Mars is a tricky object at the best of times...especially visually.
The problem is that its albedo (or surface features) are very subtle and often hard to discern in telescopes of even twice your aperture.
You need really good conditions and a very well trained eye to make the details out.
I think you might struggle a bit with the etx 125 as far as Mars goes.
What eyepieces do you have?