Weight gain and feelin blah...

So...since Emily, I've lost 41 lbs...however since a few weeks ago, I've gained about 5 lbs back!  :(  I've got to get control but it seems when I gave birth to our daughter, I gave birth and lost my self discipline for bad eating habits as well!  It's so depressing!  I LOVE my job but it also has to do with the fact that I sit at my desk all day everyday too.  With this said, I'm just feeling a little "blah" today.  So tired too and I guess that doesn't help.  I am a member of  the What To Expect website's March 2010 babies forum and we do this thread on "30 day shred" and I just can't participate, because I've not done anything to shred anything.  I think it would help me if I got back to doing excersizes but at the same time, I don't get home til 6, Em has to be fed around 6:15-6:30, then it's bathtime for she and I (she takes a bath with me) then we get out, have a little family time with her and by then it's close to 8 so she's gotta be fed again and then put to bed by 9...by the time she goes to bed, I'm truly exhausted, so yeah, no time for excersize.  *sigh*  What to do?