I have a good routine and a long list of tasks to complete. But sometimes for a few days or weeks I go completely off the routine and don't even check the task list. Then its all games, reddit & twitter, followed by lots of guilt and even longer list of personal & professional tasks. I need suggestions to avoid falling off the routine as well as tips to get back onto the routine asap. Thanks in advance.
It's difficult to tell what causes your lapses in routine. A few different causes come to mind:
1) It may be just that you don't get enough free time in your regular schedule, so once in a while your mind rebels and refuses to do work at all. As the other answer says: make sure you get enough sleep, food, and breaks. Don't work long hours or weekends. Make sure you get some physical activity once in a while - it can do wonders for improving your concentration. Make sure you use your free time well and don't worry about work while you're not working, so that you actually feel rested and relaxed when you're back at work - otherwise you'll always end up just having a "short-term burnout" and ignoring work altogether for a while because there's no other way for you to to stop thinking about it.
2) It may be that your work isn't well-defined: you don't have a good priority list, or schedule, and you feel like you're working forever and not accomplishing anything or just not accomplishing enough. Try to improve your scheduling, keep track of your accomplishments for each week to make sure you remember you did do something useful (it's amazing how often I feel like I didn't until I check my list!). Perhaps adopt a specific productivity system such as GTD or Pomodoro - there's a lot more on those on this site, and I'm not an expert.
3) It's also possible that you just don't find your work interesting or challenging enough, and you should try to change it or move on to something else. Or, if you can't move on, find a personal project that will satisfy you, and try to find at least small things you can do differently at work that will make you feel like you're doing something interesting.
How to get back to the routine - I see a few different good approaches here:
1) Start by redoing your priorities list and deciding on a few things you should get done in the next few days, without worrying about whether you should have done those things already - concentrate on the future rather than the past, and set yourself specific and achievable short-term goals. This is the best option, but may or may not be possible, depending on just how low your motivation is.
2) Just pick something you know you'll enjoy working on, even if it's not on the top of the priority list, just to get you started. This is not the optimal solution, but if the alternative is guilt and lack of motivation keeping you on reddit and twitter for another day, it's better to at least start working on something.
3) Another solution that's not perfect but it's much better than nothing, and I've employed it successfully in the past when struggling with severe motivation issues - go on a mixed work/fun schedule. Set your computer to chime every fifteen minutes, and do just fifteen minutes of work, then fifteen minutes of games or whatever you feel like. Adjust the timing and ratio however works for you. The main point is to start doing just a little bit of work, rather than feeling crushed by the idea of having to do everything and thus not starting at all. Remember, on the first day even doing ten minutes of work in an hour is better than nothing! ;)
In any case, remember that while getting back to work after you fell off the routine is important, it's more important to figure out a routine you're not going to fall off of (if only because the routine includes "scheduled fall-off periods" for relaxation).
Your body works on energy (food, sleep) which powers your willpower. The more willpower you have the better you can control what you do.
If you work long hours and don't replenish your energy, your willpower will weaken. Thus you will be more vulnerable to impulsive 'enjoyments' instead of holding them off and working for a 'post-poned' reward.
My advice: Eat healthy, get enough sleep. Get enough breaks during the day. With plenty of willpower, you will be able to defend yourself better against impulsive behavior.
Try to keep your energy high.