I know too well firsthand, the true benefits of exercise.
Right after college, I slowly became a couch potato as I dived
head-on into establishing my career. All that overtime, all that
social eating, and all that additional weight! 
What first encouraged me to reverse the cycle was, let's see, more
than 10 years out of college, in my last year in nursing school in
Nanyang Poly. Damn SUAY!! My batch was the first batch that had to
do the IPPT!!!
I didn't know the range of my
cursing vocabulary until then!

I tried to weasel my way out of it. First, I asked the coach if
there was an 'age limit' to IPPT. But DRATS!!! He said that there
were different ranges for different age groups! Doubly SUAY
man!!!
Next, I conjured up imaginary ills and made excuses to the coach,
hoping I could be excused from IPPT totally. Drats... have to
produce valid certification from a GP to be excused.
There goes all my hopes.
I really had to drrrraaaaaaaaaaaaaaag my feet to the IPPT. Worse,
half the nursing school population appeared to be there at the same
time!! That means, if you do the Standing Broad Jump and landed
SPLAT! like some malformed duck, EVERYONE would be talking about
it!!! If you attempted Sit And Reach and aiyoh...
cannot even touch your toes, people will
giggle and laugh at you! If you did the Shuttle Run and skid and
fall on your fat arse, oh glory, you will be the poster child of
clumsiness and the new mascot for the unfit the next day!
DREADFUL!!!

BUT...
Though I didn't train for it, I did pretty ok. Failed overall but
there were much younger peeps who did much worse than me. Hey, I
failed my 2.5km run by just a wee 3 mins! Not too bad for someone
who had been a couch po-tah-to for donkey years!
At least, I didn't give up 1/4 way through, like a few
young 'uns did! 
That made me think... I'm not THAT unfit afterall!! My general
fitness level is pretty good. I ought to take advantage of that and
start working on getting fit again.
So, there you go! There were times when I failed and wandered far
far far away from my goal, but slow and steady wins the race!

Now, I'm injured and all exercise plans have to be shelved until
full recovery, and I'm really upset that I have to miss all my
exercise classes.

Exercise changed me from a sluggish, drowsy person to a livelier,
more energetic, confident and a tad less moody than I used to be.
(Yes, excess fat does predispose one to depression and moodiness.)
I cannot imagine NOT exercising now... well, not for too long a
period anyways!
I love that 'I'm on Top of the World'
feeling after every workout, that flush in the cheeks, that 'We are
the Champions' kind of ooomph! 
The benefits of exercise? You bet!! 