Strength exercises build muscle as well as increase your metabolism, which helps keep your weight and blood sugar in check.
Safety tips:

•    Don’t hold your breath during strength exercises. This could affect your blood pressure.
•    Use smooth, steady movements to bring weights into position.
•    Avoid jerking or thrusting movements.
•    Avoid locking the joints of your arms and legs into a strained position. Breathe out as you lift or push a weight and breathe in as you relax.
•    Muscle soreness lasting a few days and slight fatigue are normal after muscle building exercises.
•    Exhaustion, sore joints, and painful muscle pulls are not normal.
An easy excercise routine
1.    Sit in a chair with your back straight.
2.    Keep feet flat on the floor even with your shoulders.
3.    Hold hand weights straight down at your sides with palms facing inward. You can use as little as one or two pound hand weights or you can substitute cans of soup. Some people start without weights. Arm raises.
4.    Raise both arms to side, shoulder height.
5.    Hold the position for 1 second.
6.    Slowly lower arms to the sides. Pause.
7.    Repeat 8 to 15 times.
8.    Rest. Do another set of 8 to 15 repetitions.
Chair Stands strengthen stomach and thigh muscles.
1.    Place pillows against back of chair.
2.    Sit in middle or toward front of chair, knees bent, feet flat on floor.
3.    Lean back on pillows in half-reclining position, keeping your back and shoulders straight.
4.    Raise upper body forward until sitting upright, using hands as little as possible — or not at all, if you can. Your back should no longer lean against the pillows.
5.    Slowly stand up, using hands as little as possible.
6.    Slowly sit back down. Keep back and shoulders straight throughout exercise.
7.    Repeat 8 to 15 times. Rest. Then repeat 8 to 15 times more.
Bicep Curls strengthen upper-arm muscles.
1.    Sit in armless chair. Keep feet flat and even with shoulders.
2.    Hold hand weights at sides, arms straight, palms facing toward your body.
3.    Slowly bend one elbow, lifting weight toward chest. Be sure to rotate palm to face shoulder while lifting weight.
4.    Hold position for 1 second. Slowly lower arm to starting position.
5.    Repeat with other arm. Alternate until you have repeated the exercise 8 to 15 times on each side.
6.    Rest. Then do another set of 8 to 15 alternating repetitions.
Source : National institute of health