Good morning exercise. Feet shoulder width apart. Place a barbell "in the groove" of your shoulder and trapezius (no weights). Bend down slowly. Keep legs locked. Hold for two seconds. Return to starting position. For more resistance, add a little more weight. CAVEAT: Do this slowly. Jerking or rapid reps can do more harm than good.
Variation on the squats I mentioned. This is a great exercise for almost every part of your legs but, as "Tude says, can cause problems if not carefully done. For years I've preferred to do these holding 40-50 pounds in sand weights near my waist or between my thighs, as oppossed to being topheavy with arms at shoulder-height. For me it's always been too easy to lose balance when my arms and weights were up high, so I keep them close to my center of gravity. Keeps me from teetering and tottering too much and putting extra strain on my knees, which I don't need at my age.