Age is not essentially a factor in deciding the workout of an individual, though physical morbidities may limit ones ability for a complete physical
workout; since excessive physical
workout, unlike that in the younger years; may aggravate the degenerative processes in the joints. Though hypothyroidism is associated with some amount of myopathy in some individuals; since you have not mentioned any rheumatological, ortho or neuro-muscular condition, I assume you are otherwise fit.