Dancing

Social dancing, besides being an entertaining activity, has a lot of benefits. 
First and the most important, you work out your body, your muscles, while for the brain, it is a very very relaxing activity... you can detach completely after a stressful day at the office /job (especially for people who have static jobs like IT <being "stuck" in front of a PC all day>). Besides exercising your body (that you can also do in a gym class or aerobics), dancing is a fun and enjoyable activity. In time you get multiple benefits: good body equilibrium, hand-body-legs coordination, rythm.
Since social dancing involves a pair (two people)  it can become a way to spend some quality time with your "loved one"; even though, I want to add that it's not mandatory to take a class with a partner, it's also a way of socializing with other people who share the same hobby as you and the same positive feelings towards dancing. 
Even though I practice sport-dancing as a hobby (in my free time, not as a professional dances), so for me it's more like "social dancing", I enjoy and support also similar dances (Argentin Tango, Salsa, and so on). It's the love of music and the dance-floor those have in common and it's great :-)  

Funny facts about taking up social dancing

Our little collection of dance-memories