When is a good time to settle when suffering a personal injury at work?

I had a part time job and suffered an injury. Now this injury was an injury that healed and was re-aggravated with the mishap at work. The injury is slowly healing, and I've been told not to work in this line of work again (manual labor). The first time that the injury happened it healed completely, and I was able to resume my normal daily activities. However, since the injury has been re-aggravated I've gained a tremendous amount of weight, and I cannot resume daily activities. The have offered a settlement, but based on the information I'm not sure if I should take it or not.