>>96921981
When you think about models, you probably imagine what they will look like when they're finished, right? So you get excited and start building, because that doesn't demand a lot of your time and is fairly easy and immediately rewarding since you get abunch of loose parts into a model. Something your mind is very good at is cost-benefit analysis when considering a future reward, but unless you cultivate a love of the work involved to get there, your mind doesn't include the painting as part of that plan. So, when it's time to paint, since it's a lot of work and doesn't feel like it's getting you closer to your goal in a timely manner, you start thinking you'd rather do something that is more rewarding in the now than commuting a bunch of time and effort into something that'll come later.
So, get used to enjoying the painting, or at least keep front and center in your imagination the painting effort involved, and it won't be so de-motivating when you get to that part.