Whether you're an avid swimmer or not, swimming has obvious benefits as opposed to other forms of exercise. With the lack of stress on joints, save perhaps shoulders, it is an ideal activity for all ages and is often used for physical therapy.
I have been swimming since I was just 5 years old and although learning how to swim can be a challenge it can be rewarding in ways I have only begun to realize as I venture into my early twenties. If you ever see older people swimming at the local YMCA then you're not alone, or the ever-exclusive women's water aerobics (aka gossip club). But, the fact that you see these older people in the pool tells you something. It shows you that the water is the most accepting medium for exercise.
So often you hear about sports injuries and people requiring rehabilitation due to joint or tendon issues, but swimming has allowed me over the years to maintain peak conditioning while making sure recovery is always easy. If you say, "Swimming is too hard" or "I'm just bad at it" that's OK. You don't have to be good at swimming to get a workout, and it doesn't take long for you to start learning how to make it easier. Swimming is simply fantastic, it works practically every part of the body all at once.
If you're still convinced you're not a swimmer then consider this: swimming in general helps speed up your recovery of muscles. What this means for athletes and others is that you can get an edge on your competition by speeding up your recovery process which ultimately means you can workout harder and more often than the other guys. In college swimming we often times warm-down after an intense exercise which helps get rid of the lactic acid built up in our system. So basically, by swimming (light to medium paced) you can get rid of that lactic acid that causes soreness and prevention of muscle building.
Swimming helps build muscle!
So why wouldn't you start using your local pool? Even if you just jump in for 30 minutes it'll be one of the most important 30 minutes of your workout week. After all, there's a reason why people marvel at the "swimmer's body", the water lets your body do things it normally could not. So BE SMART about your workouts and include some swimming, if nothing else to just rinse off after lifting.