No matter how much we may know that we lose strength when we age, it is quite a reality check when simple tasks are no longer easy. Resistance training is not something to put off. 

Here are the suggested minimum requirements:

Train 2x/week

Perform 8-12 repetitions of each exercise

Perform 1 Set

Use 75 percent of your maximum resistance

Go slow and use the full range of motion

Remember, this is the minimum requirement!  More is better.  This 2 days/week program is if you work your entire body at once.  I split up my body working my upper body one day and my lower body the next.  Sometimes, I will do legs and shoulders one day and perform chest, back, biceps and triceps the next workout.  At other times I focus on glutes and core.  I have been at this a long time so I get bored.  Two or three days per week of total body conditioning may be the best if you are not used to a training routine.

Things to avoid if you are a senior:

Intense straining, holding, hanging, or pushing.

Lifting very heavy weights.

Continuous raising or holding of the arms overhead

Exercise that is too intense.

Here is a list of benefits from getting into a training routine. I am sure you know many but it is a gentle reminder.

Increases muscular strength

Retards Osteoporosis

Retards Lean Body Mass loss

Improves flexibility

Increases the ability to recruit motor units (Hypertrophy)

Statistics aren't sweet when we talk about aging.  By age 70, most people have lost 30 percent of their strength and flexibility, Women lose 30% of bone mass.  All have a decrease in their basal metabolic rate and an increase in fat storage.

Neurological effects of aging occur as well but are lessoned somewhat by an active lifestyle.  This is a fight folks!  Attack it with a positive attitude, workout buddy, and determination,  Be proactive so that you can avoid feeling miserable down the line and please be gentle on the joints.