In the top two images there is some space described between the foreground and background, but what if you wanted more? The usual adjustments might do the trick;
Color: Make the background cooler or the foreground warmer.
Value: Compress the range toward middle value in the back ground, or exaggerate the darks and
lights in the foreground.
Wetness: Make the background much softer.
Composition: Can you enhance the illusion of space by rearranging the location of the major shapes?
What if you made all of these changes? In other words, why not maximize the differences between foreground and background? There may be a good reason why not, but let's have a look. Turn the dials all the way!
The image of the lake has a lovely streak of sunlight on the far shore. What might you do to intensify that light?
Some students are uncomfortable exaggerating the colors or the composition of a scene. It may feel like lying, or failing to do justice to the subject, as if we are meant to do the best we possibly can to duplicate reality. I believe our job is to interpret the subject in a way that displays our personal connection to it. Think of the origin of the word "Art", as in "Artifice".
If you work from your own image, please bring a print of it so we can see the changes that you made.