I have a 3d model that is already rigged and does have a few animations already. I have a run animation that doesn’t really look like running but more like a fast walk. I’ve tried tweaking it myself but to no avail. Any help would be greatly appreciated! Thank you!
what about using a mixamo running animation/rig?
I’ve tried Mixamo but bag becomes distorted (first 2 images). I’ve also tried Rokoko and that becomes distorted as well. With Rokoko (last image), it might be because of where my bone cursor (highlight) is at?
depends on your weight paint and how the model geometry is. I think it would be much easier to help if you could provide a blend file with a try of yours (e.g. the one from mixamo)
Here is the (fast walk) run animation in Blender if anyone would like to give it a shot.
Bag Model run.blend (4.1 MB)
Using mixamo or rokoko to animate this character isn’t going to work. This character (didn’t look at the file, so I’m just guessing here) doesn’t have a typical humanoid rig to it, so re-targeting tools won’t work on it. I just found out that those tools only work for what appears to be a fairly standard human biped rig. To get a simple rig like this to work with mocap data would be a bit of work.
More than likely that is what the run animation is, a fast walk cycle. When walking, one foot is always planted on the ground. When running, both feet leave the ground at one point, and movements are more exaggerated, shoulders and hips rotate further than when walking.
I’m regret saying this, but really there aren’t alot of animators around here…
Maybe look up run cycle animation references?
What’s the end use?
Randy
Could look at it as a humanoid with just an oversized bag over it, like a person wearing a bed sheet to look like a ghost. 
End use is for a video game that I’m currently working on. Baghead is the main character.
I don’t know how “perfect” it has to be and if it helped you,
but i imported a running animation from mixamo.
Then i deleted the hip and one animations of the bag.
Then i copied the hip and bone animation from the mixamo rig to your bag rig.
result:
I know it is not perfect, but i think it is a good start to tweak the animation.
Hello. Is this a volunteer job?