anything wrong with doing an hour or so of lifting, getting bored then coming back and finishing off later?
You'll be slowing down your exercise.An hour? Well, unless you're consuming 2000 calories in between, not really.
You shouldn't be doing more than an hour of lifting in the first place.But you could do say, your upper body then go eat and digest for a few hours and then come back and do the lower body for example.