Do you rest enough?

A good training plan is about balance - rest can be as important to achieve your goals as the workouts themselves.  Your training plan should also gradually build - you don't want a plan where you just plateau.
Rest should be a key factor throughout your training plan. Its a good idea to have at least one day of rest and potentially two if one is active rest.  Active rest could consist of numerous options, a nice walk, yoga, gentle bike ride, anything that gets you moving but doesn't exert yourself. 

If you are strength training, it is wise to rest muscles groups for up to 48 hour.   Your plan can include one muscles group one day and another the next.  If you were building a running programme you could include one long run, a session with sprints and jogging, a medium run at a steady pace and a short run at a faster pace. 

If your workouts are more bootcamp / circuit based you might plan a cardio focused session, a session focusing on the arms, one on core and one on legs.  You may even wish to mix up the way you set out each session, the "rests"  between the exercises could be active rest, cardio bursts or even actual rest!  Plan you sessions so you have three hard workouts and one really tough one.

Ideally your training plan should gradually increase.  For example if you were running the long run would increase in either duration or distance, the paced runs would increase a little in pace each week etc.   With strength training you might increase the reps or the weight gradually.  

Ideally you should build you training up gradually over a period of four weeks.  The fifth week should be your rest week. A rest week doesn't mean that you do nothing, but you dial your training back and reduce the intensity for a week.  For example if over the four week period you had increased your long run 5 mins each week from 30 mins to 50 mins, you might dial it back to 40 mins on the rest week.  You may also reduce the number of sessions you do replacing one with active rest instead. 

A week like this gives your body chance to repair and recover from exercise, allowing you to keep building on your training. 

If you have a really tough and intensive training routine, you may benefit from an entire week of active rest after 8 weeks of training.