Group the Third and final (unless some poor bastard needs hypermobile neck strengthening stuff or a psoas stretch), the lying on the side!( Arm Lift )
If your arms/shoulders don't bug you, don't worry about this.
---( Arm Circle )
If your shoulders don't bug you (or make alarming crackling noises that kind of hurt), don't worry about this.
---( Leg Lift )
---( Bananas )
This one makes you look like a hooked fish; if anyone laughs make them join you on the floor.
I feel obliged to point out that before doing exercises, you may want to roll out areas that you know tend to be tight. This can be done with a foam roller, assuming you have one, or smaller areas can be tackled with your friend, the Tennis Ball
Foam rollers or bigger balls (smaller than your head but not by that much) are excellent for getting big muscle groups to let go and do their own damn jobs, not steal other muscles' jobs. Think quads, sides of bum, bum proper, hips, that sort of thing.
Tennis balls, Franklin balls (which are a bit bigger but mostly a bit softer
than tennis balls) and related sizes are good for smaller areas like shoulders, calves, the outsides of hips, which will also try to redistribute work orders based on who's on vacation and who's the workaholic in the office.
I also feel obliged to point out that shaking like a leaf, especially if it's your lower belly, is actually a sign that things are going very, very well. A weaker muscle is being worked, and if you keep after it, will get stronger and you'll not only shake less, you'll be able to do more with it. (The trick is finding the stopping point between 'shaking like a leaf' and either pulling something or having a secondary system jump in to be Helpful.)
Personal trainers, pilates instructors, physiotherapists, that housemate with the anatomy colouring books and the gleeful grin, the Internet, and others can be really, really useful in helping you troubleshoot. Make use of 'em.
Most of all, pay attention to your body. What motions bug you? Where do they do it? How does it feel? The more specific you can be when talking to a professional (or the Internet) the better troubleshooting you'll be able to do. Even a 'My shoulder hates me, but it's worse when I do [...]' is helpful.