Trying to get the most out of your exercise regimen can be difficult if you are pushing yourself too hard for just a few days out of the week and finding yourself tempted to skip days due to the levels of exhaustion that you hit. There is also the issue of time consumption as it is very difficult to set aside a few hours all at once to just exercise. Even worse is when you find yourself making excuses for why you cannot commit to an exercise regimen and then just not exercising at all. This is why quick daily exercises can be immensely helpful and still very beneficial to you.
Some basic fitness exercises to keep in mind: pushups, crunches, pull-ups, and running. Pushups are a low-intensity exercise that will build lots of fit muscle and not take very long each day to do. Even a quick regimen of twenty to twenty five pushups four times a day will get you into shape fast without taking up a lot of time. You can space it out even more depending on your current shape and goals, possibly keeping it to only fifteen or twenty pushups a day total. This will build your arm muscles without causing any kind of straining or other issues.
Do you want abs? Great abs come from one thing and one thing only: utilizing your abdominal muscles. You can very quickly and easily utilize your abdominal muscles with crunches or sit ups. Just fifty crunches a day will take you a few minutes and develop great abs over a few months. Crunches are not a miracle exercise though and abs will not immediately show up through layers of fat tissue but this is healthy and normal. You will still have well developed abdominal muscles and over time as your fat burns away, your abs will become more prominent and show up much more.
Pull-ups work very similarly to pushups in that you are utilizing your body's own weight into order to build arm muscles. These take virtually no time at all but doing more than a few pull-ups at a time is incredibly draining and it is difficult to maintain the number of pull-ups you can do in a rep. It is a good idea to set a low initial number, such as five pull-ups per rep and do five reps a day. You will develop a lot of lean muscle like this without spending hours at a gym.
Finally, there is running. Running is the epitome of exercise and it really gets your heart pumping. Running takes a bit more time than any of the other exercises, but the more time you devote to running the better it is for you. That is not to say that a twenty-to-thirty minute jog every day will do nothing for you, though. Quite the contrary, even a little bit of running will substantially improve the amount of energy you have, burn a lot of weight, and really develop your leg muscles.