It's almost 6 p.m. and you just couldn't pull yourself away from work to get in a workout until now. The only problem is, the sun is going down and you won't be able to fit in your normal 45-minute routine.
When you're short on time, definitely don't skip out on your workout, and don't give up on getting in a good sweat session. Use the time you have to push yourself twice as hard. Move a little faster, add incline to your run or bike ride, do faster sets of strength training moves, increase the size dumbbells you normally use, or do something new that will work weaker muscles. Short workouts at a high intensity can be great for burning mega calories and for endurance, so use the time you have to work it.