The jury instructions (those instructions a judge reads to a jury just before deliberation) discussing this issue state the following: "On this issue, the burden of proof is on the defendant. This means the defendant must prove, by the greater weight of the evidence, the amount, if any, by which the plaintiff's actual damages should be reduced because of the plaintiff's unreasonable failure to avoid or minimize his injuries."
Further, the plaintiff must "use that degree of care which a reasonable person would use under the same or similar circumstances to seek treatment, to get well and to avoid or minimize the harmful consequences of his injury."
In other words, if the plaintiff could have avoided the damages by acting reasonably — to alleviate his or her pain or suffering — he or she would not be able to recover for those damages. It is important to note that for the at-fault party's defense to work, this failure to avoid these damages must be found to have been unreasonable.