What did you like to do when you were younger? Maybe it was dancing or kick ball. Maybe it was frisbee or basketball, or maybe doge ball! You can recreate all of these sports even without Coach Dan and get some great bursts of cardio in.
Go pick up a frisbee and get out on your front lawn. If you have children, they will be begging to play every day.
Get a pair of 25 pound weights and keep them in your bedroom to do mini-lifting sessions anytime. You'll build up to a routine in a short time.
Have a lifestyle where you can't get to a club to dance (or maybe you simply don't want to!) Blast your favorite music on your ipod or computer right in your living room and dance. Even if it's for 5 minutes you'll feel that same rush.
If you played basketball, football, swam, soccer, whatever it is, there is a local organization or gym or community gathering of the sport. If you simply didn't like sports or activity when you were younger, this is the best time to pick up something you've always wanted to do.
Coaches and trainers love that you are brand new because they don't need to retrain you from bad habits. Tennis is a great example of this: it's much easier to teach someone to swing with the raquet down low if they've never done it, vs teaching someone who has been swinging a certain way for 15 years.
Don't be intimidated - people will love to teach you whatever sport you've dreamed about.