agonize

Short definition from Wiktionary

Verb

1. 1
   To writhe with agony; to suffer violent anguish.
2. 2
   To struggle; to wrestle; to strive desperately, whether mentally or physically.
3. 3
   To cause agony or anguish in someone.
4. 4
   To act as an agonist upon; to combine with a receptor on a cell to produce a physiological reaction.