He sharpened his will and pressed on without slacking off.
Tips
usage
砺 is a rough whetstone, and by extension 'to temper'. The key word is 砥砺 (to hone, to encourage), used for steeling one's character or spurring others on, as in 砥砺前行 ('to forge ahead').
The stone radical, picturing a rock. It is the meaning core: a 砺 is a coarse grinding stone used to sharpen blades, hence the wider sense of tempering.
