If they weren't so busy with the ostrich plumes and grape peeling I would just let the porters do it.
One idea, taught to me by a friend who served in Viet Nam was to stick one knee straight up with your foot still in and touching the hammock. Move that knee left to right a few times, then straighten your leg back into normal position. Depending on the amount of sag, you might have to try a couple times to get the rhythm right. He is retired army lrrp. They used Vietnamese made hammocks pitched fairly snug, and low to the ground. That technique works very well in my bedroom sleeper, and with the commercially made one strung up in the backyard.
The other stupid one is to lie there, stick your elbow up in the air with your fist near your nose. Move the fist about a foot away, and move your arm left to right bending at the shoulder. (Dare I even mention that vogue type Britney Spears video thing for comparison?.. eh.. no. Whoops! Too late.) Arm goes to the right, you'll swing slightly to the left. Same rhythm thing may apply. Again, both work for me.
Lastly, and the most stupid looking of all would be to just stick one leg/arm up in the air, and move it slowly left to right. Works, but looks strange and requires too much energy from the "relaxing" position.
YMMV contact your attorney for details, point away from face when opening, etc.
I used to tie a line to my canteen, then tossed the canteen over into the shade and used the line as a swing string. If I got thirsty, I hauled in the canteen.
I have been searching for an automated rocking chair (that allows your legs to stretch out). Years ago there was something called the Ghost Attic but it was for a large swing and I think the mechanism was hidden in the porch ceiling. In any event, they never got to the point of selling it. I've seen the hammock swing but that rocks side to side.
I've asked my husband if he can make it but he's had chronic pain for years so that's out.
I'm hoping I will find someone that can make this for me. I am in the middle of fighting MMMT (a rare aggresive cancer) and I also have quite a bit of anxiety. I also think it would be a blessing for people with pain, also for those who are hyperactive, etc.
Seems to strange to me that no-one has cashed in on this.
Would love to see if anyone else has found something like this online.