@layman,
In GR, the notion of "inertial" motion is reversed. A planet orbiting the sun is said, in SR, to be "accelerating" because it is constantly changing direction and sometimes speed, too.
In GR, that planet is said to be in "free fall," which is, in GR, "inertial motion" from what I understand. Whatever you call it, it is gravity that causes it to follow the path that it does, and move at the speed that it moves.
Not particularly relevant to either LR or SR, on the surface, anyway, but kinda interesting that the same motion is inertial under one theory and accelerated under another. There could be something deeper there to understand, but I wouldn't know.