His vigorous stride is shortened, and his own schemes trip him up.
The rest of Bildad's discourse is entirely taken up in an elegant description of the miserable condition of a wicked man, in which there is a great deal of certain truth, and which will be of excellent use if duly considered - that a sinful condition is a sad condition, and that iniquity will be men's ruin if they do not repent of it.
Commenting on Job 18:5-10
For he is cast into a net by his own feet,.... He goes into it of himself, incautious and imprudent; the counsels, schemes, and methods he takes to hurt others, issue in his own ruin; the pit he digs for them, he falls and sinks into himself; and the net which he has spread and hid for others, in it is his own foot taken...
steps of his strength--Hebrew, for "His strong steps." A firm step marks health. To be straitened in steps is to be no longer able to move about at will (Pro 4:12). his own counsel--Plans shall be the means of his fall (Job 5:13).