George Long's 1862 translation, public domain, so it is checkable.
The passage opens with Marcus saying that in one respect a man is the nearest thing to him, because he must do good to men and endure them. Then he adds that so far as some men make themselves obstacles to his proper acts, a man becomes to him one of the things which are indifferent, no less than the sun or wind or a wild beast.
Only then does the familiar sentence arrive: the mind converts and changes every hindrance to its activity into an aid, and that which is an obstacle on the road helps us on this road.
The slogan travels attached to circumstances. Setbacks, illness, market conditions. In the source, it is attached to a person who is getting in his way at work.
That is a much harder instruction, for a reason I think is worth naming. A circumstance does not have intentions. A person blocking you does, or you believe they do, and the belief keeps running after you have left the situation. The obstruction is not the expensive part. The interpretation is.
Worth flagging the limit, because it gets stretched. He does not reclassify the person as indifferent. He reclassifies the obstruction, and he opens the entry by affirming the obligation to do good to them and endure them. It is also plainly about ordinary friction rather than anyone being harmed.
Source: r/u/zaidshaiba · by /u/zaidshaiba