Usually alone. I like to walking in the mornings when it's cool and my allergies are at bay. Sometimes I wished I had a partner to keep me motivated and say let's walk one more block :)
I work out alone but wish I had a workout buddy to keep me accountable. I have walked in the past with a friend at the beach once a week and it really helped to have a date set, time and place to be, to walk. It sure helped me lose weight. Since it is summer, getting to the beach before it gets too crowded is nearly impossible.
I tried working out with my sister in law and she was "oh, I can't do it...I just gotta sit down"...lol...so I work out alone :0) I have enough problems trying to motivate myself everyday!
I generally work out alone. I do see lots of walkers, though, when I do my walks outside. I just prefer having that time to myself to just think and clear myhead.