Forget to hydrate
So many people are dehydrated to some degree most of the time. It is recommended that you drink about 30-35ml of water per kg of body weight each day. You should also take in an extra 500-1000ml for every hour of exercise. It is quite clear that if you lose a lot of liquid through sweating, it needs to be replaced.
Eating too many calories
Eating a load of empty calories post workout is a really bad idea. Because of the strain that you have put on your body during exercise, it is good to eat something easy-to-digest. Protein, carbohydrates and a small amount of healthy fats are perfect for starting muscle repair and nutrient replacement.
Both before and after a workout. I don’t need to say more.
Just do it!
Doing nothing else for the rest of the day
Don’t think for a second that doing a workout session allows you to spend the rest of the day on the sofa doing nothing. Of course, there is nothing wrong with the odd lazy day; just don’t make a habit of it. Try making movement a part of your day. Use the stairs instead of the lift, get up from your desk for a quick walk every hour.