Gym for me.
I started with water aerobics class. My joints thanked me for not overstressing them in the beginning. I can't afford to have a pool at the house.
I made casual friends in the class and that led to accountability and repeatability. We keep each other committed to going. A couple of them go to the same church as I so we have an additional dimension of connection but don't do much other than lunch once or twice a year when the planets align correctly.
I have had benches and barbells and dumbbells, etc but I always seemed to fall back on the "I'll do it later" excuse. I've had treadmills and ellipticals - same thing. I have DVDs too but I don't have a good place to do them. My pets like to get in on the action and distract and disturb my concentration.
I'll admit it was hard to go that first time to add in weight lifting and then bike intervals but it was all in my head. I can recognize the regulars for that time of day and we greet each other. Nothing overly social - just a pleasant good morning and maybe a brief comment about the weather. Maybe its the early hour that I go but I never see anyone flirting and carrying on. Pretty much everyone uses their iPods or MP3's. There are a couple of older busybodies (male and female) but I try not to make eye contact.