try (one's) damnedest
To put forth the maximum amount of energy or effort toward some task or goal. Money is a little tight at the moment, but I'll try my damndest to be there for your wedding. I'm trying my damnedest to get a passing grade in this class.
do/try your ˈdamnedest
(informal) try very hard; make a very great effort: He was doing his damnedest to make me feel uncomfortable so that I would leave.