For with little external to constrain us, the innermost necessities in our being, these still drive us on.
The fetid closeness of the air, and a famishing diet, united perhaps to some fears of ultimate retribution, had constrained them to surrender at discretion.
But all we said, not a word could we drag out of him; I almost felt like pushing him over, so as to change his position, for it was almost intolerable, it seemed so painfully and unnaturally constrained; especially, as in all probability he had been sitting so for upwards of eight or ten hours, going too without his regular meals.
There are no more uses of "constrained" in the book.
Show samples from other sources
...it is very grievous to be constrained to keep our hands off such a dainty dish as Narnia.
C.S. Lewis -- The Horse and His Boy
It seemed that we were all cloaked in an unwelcome garment of racial difference that constrained, confined, and restricted us.