There are definite phases in life where working out gets old. When you reach these points, the best thing you can do is shake things up a bit. Make your workouts fun by doing something different. A great way to make your workouts different is by racing against yourself. Add a timer to your workouts, and try to beat your time the next go round.
You can do this with…
A ___mile run
A 1/2 mile sprint (or any distance for that matter)
100 Burpees
A certain circuit workout that you love
Your favorite running trail
A flight of stairs
Your own fitness obstacle course
Etc.
You get the picture. Give yourself a challenge! You will feel motivated to try harder when you know what you want to beat!
You can do these with or without weights. Open your legs up wide, with your knees and toes facing out. Squat down as low as you can, and then stand back up and tuck your hips under. If you want to hold a kettle bell, some dumbbells, or a bar to make it more difficult, go for it!