How can i increase my energy levels?

Several suggestions: Exercising and eating right is my first recommendation to you. You should have your primary run blood tests to ensure you are not suffering from B12 or folic acid deficiencies. A CBC should be ordered to rule out anemia as well. Declining kidney function is also associated with fatigue. Several infectious diseases (ie Hep C) is also associated with debilitating fatigue.

It depends on...: I need much more info to answer this. If you are basically healthy but want more energy make sure you get adequate sleep, eat a healthy diet, take a quality multivit., practice stress reduction, exercise and try herbal tonics like ashwagndha and rhodiola. If you suffer from significant fatigue see a good Dr. to find the cause- could be anemia, chronic infections, hypothyroidism etc. See comment:

More energy: (1) Make sure you're getting 6-9 hours of sleep on a regular schedule. (2) Eat small frequent meals (every 3 hours or so) containing lean proteins and complex carbohydrates. (3) Supplement multi-vitamin and B complex. (4) Maintain a positive outlook towards life. (5) Get baseline blood testing done, if you have not to this point.

Live healthy: Early to bed and early to rise. Good well balanced diet. Daily exercise. Avoid alcohol and illicit drugs. Balance and moderation in all things.

Not enough info: You need to provide more specific information. Are you overweight? Do you take any meds and if so, what are they? Do you have any significant medical problems?