Using partial keyframes

The first example used all the keyframes to generate the motion. As a result, the motion went from T-pose to T-pose. This can be easily adjusted.

Go back to the timeline view and pose mode

Now you should see the keyframes for each joint individually.

Let's remove the keyframes for the arms and legs.

To do so select the keyframes that we want to remove and press X and then Delete Keyframes

You should be left with only keyframes for the hips, spine, neck and head.

Now if you click generate the animation will ignore the positions of the arms and legs.

Here we removed the keyframes for both the 1st and 128th frame, but you could for example only remove the keyframes from the first frame. You could also add partial frames inbetween the first and last.