Medicine balls are a great way to help strength and lose weight. These are easily available at sports stores and aren't expensive! Below are some simple exercises you can do at home.
Standing Figure 8
Stand back-to-back with a partner and exchange the ball behind your back at waist level as fast as you can, receiving on one side and returning on the other side.
Similar to the figure 8s, but this time throw and catch the ball with fully extended arms instead of handing.
Stand in a normal hitting stance holding the ball in both hands level with your back and shoulders. Throw it forward with maximal effort in line with a normal swing.