Plan for the next day at the end of the day
Nutrition seems to be one of the hardest things for people to nail down, so foresight is your friend. Set aside some time at the end of the day to get some food ready for the next day, so you aren't stuck guessing what you are going to be eating, hoping that it's good for you!
Set realistic goals for yourself every week
Saying that you are going to lose 15 or 20 pounds by the summer is a bit unrealistic, and hard to grasp because it is too far away to really be tangible. Instead, set realistic short term goals for yourself so you can check your progress. Saying, "I will cut white carbs out of my diet this week", or "I will work out 5 days this week" are short-term goals that you can see, check on easily, and you actually have a plan on how to do them. Much better approach to long-term success!
Use your calendar as an attack plan
Use your calendar to chart your workouts, your current weight, your weight goals for the week, meal structure, work projects, anything else that you need to do in a daily basis. Setting your week out on paper makes you more likely to actually complete the tasks you have in front of you. This is also true for your workouts; tracking what you do will give you a better way to show progress than just guessing blindly as to what you are going to do when you hit the gym.
Get a friend, or a personal trainer to help you
It's no secret that people perform better when they have someone with them during their workouts. Maybe you will have the guts to try that last rep, or your creative talents combined will produce a more productive workout! Plus, having a (smart, qualified) trainer on your side ensures that there are smarts behind your sweat.
Recognize the race ahead of you
Too many people look for the easy way out of their transformation; fat-burning pills, cleansing shake routines, "secret exercises", and other stupid things to try and get away from the inevitable fact. Reinventing yourself is not a sprint, it's a marathon. Looking to get in shape overnight with cheats & pills sets you up for disappointment. When people don't actually walk the walk, they might drop a few pounds, but almost always put that weight right back on as soon as they go back to eating what they consider 'regular' food. Do yourself a favor - clean up your fridge, get active, and set yourself up for success!