depression steming from not working out?

[sketch9007]

I am 19 years old and up until I graduated high school I either worked out played sports or something active that got all my endorphins and adrenaline going(ran XC, football, LaX, track).  Now that I am in college I have not been exercising.  I graduated spring 2008 and it is currently fall 2009.  Lately I have been working 35 to 40 hrs a week along with college fulltime.  I have felt depressed/not the same for the past year or so, could all my problems be coming from a lack of exercise?

Also this semester I got a bike for transportation to class.  I only had it running properly for 2 or 3 weeks and that was about 2 months ago.  The tire is flat/bent.  Today I’m going to get it fixed.  When my bike was operating well I had a ton of energy and always seemed to be in a better mood.

Anyways, I’m getting my tire fixed today and am wondering if a year and a half depression could be from not exercising.  Should I "bank" on this fixing my problems?

Side note... I’ve had two knee surgeries and am not a fan of working out. BUT I love riding my bike.

Thanks for any feedback and if I was too vague comment back with questions.  THANKS!

[mammo]

There are varying degrees of depression, and YES lack of exercise can get you down.  You've experienced it, do what makes you feel good, and be happy that you can overcome your depressed state by exercising and not with drugs!

[whodunnit]

In answer to your question? No.

Depression is not dependant on people exercising or not. It is far more complex than that.

Exercise is, of course, a benefit for any human being as it gives our whole system the work out it needs. But it is NOT the key to depression by any measure.

[mammo]

You're right on with this!  You are used to having a physical way of releasing energy, without that, you get down.  Exercise, even just walking will help!

[Cloudwindgate]

Its like you said you got endorphins relieased when excercising which make you feel good and often giving the name a runners high. It just sounds like you need more activity of other kinds then just school and work. More then likly you will feel much better