How can you tell one phrase's more natural than the other? 'I would probably just vs I'm just gonna' I have recently received a correction for my note below: Zach Galifianakis (ZG): (Struggling with weights) Brad Pitt (BP): Do you need a spot? ZG: Yea, if you can, that would be great. I would probably just do a couple of reps. BP: I got you. Let me know whenever you are ready. I was corrected in the last sentence of the third line; 'I'm just gonna do a couple of reps.' I'm just curious as to what makes the phrase before the correction ('I would probably just') sound less natural to the Native speakers than the phrase 'I'm just gonna'. I've heard other Native speakers using this phrase 'I would probably just + verb' (I may be mistaken though) but my guess is that it doesn't fit in this context? Or is it maybe too formal to use in a place like a gym? Or is it simply UNnatural? I'm very grateful for the generous correction but just trying to understand the thought process so I can understand it better! Thank you always for taking the time to shed some light on my question.