how di i determine wether i have to work overtime at my job my work week 40 hrs i am 62 yeras old can i refuse because it would be to hard on me

As a general matter, the employer unilaterally determines the hours of employees, unless there exists an employment contract or collective bargaining agreement. Having been required to do so by the employer, an employee may refuse but risks being terminated for insubordination. The fact that long hours are difficult or unpleasant will not excuse your refusal to perform as demanded by your employer.