The trick is not to put the same amount of detail everywhere. For areas you want to appear further back, just concentrate on your lights and darks and try to avoid any sharp edges or definite lines. Save that for the foreground.
Another thing to do is to keep your colors cooler and more muted for things you want to appear further away. Use warmer and brighter colors for things you want to appear more close up.
Avoiding putting a lot of detail everywhere isn’t lazy, it’s actually showing good artistic judgement. When you look at something off in the distance in real life, you don’t see all the detail in it. So it should be the same way in your painting.
You can see me demonstrate these principles in the video below.
Painter of portraits and wildlife