looking good so far
...I like the skin highlighting, and they look properly dirty and grungy
...I think the bases aren't too bad, but...yeah...I think I see the issue...the models are nice and dirty, right, but it's a real dark kind of dirt, and they're in a fairly light red dirt environment, so it doesn't quite fit together...maybe a coat of agrax or nuln oil, or both on the bases, and a bit of a red-brown dusty light drybrush on the lower parts of the models (like on the feet of the kanz, but maybe a touch more), to simulate dust being kicked up as they're moving along, that would probably go a long way to tying it all together I think
...and don't worry about the motivation man, happens to all of us
don't think about the whole army, or all the other stuff you have to paint, when you're trying to paint something...just focus purely on that unit/model, then the next, and so on
(I made the mistake of sitting down around new years' and figuring out all the stuff I have to work on...turned out to be easily at least 500 models, a lot of them I bought second hand, and need to be stripped too!...I only just managed to talk myself into picking up a brush again lastnight, about 3 weeks later
)
if it comes to a point where the thing you're painting is just killin ya, switch to something else for a while, then come back to it when you feel like it - it'll already be part-way done then
if you're painting boyz or something, don't be overambitious...just paint like 5 at a time...if you say, try painting a mob of 30 all at once, if you're anything like me, you'll maybe get like 3 colours on all of them, then be burnt out, hating life, and then they'll sit there half-done for months
basically, just keep chipping away at it mate, and paint often too, try not to go without painting for any more than a week, otherwise you'll have to find your rhythm again, so to speak
...it's good to be green! 
