Need help with excercise...

I am a little more than 4 months post-op RNY, 77 pounds lost so far (307 to 229).  I am doing great at the food side of things, but excercise has been really hard for me.  I have a 2 year old son who throws a fit when I do an excercise video or weights because I can't pay attention to him during it.  He lays right where I'm trying to stand and kicks me, etc.  I've done the ingoring thing, but get tired of tripping over him (not to mention I'm afraid of falling on him and hurting him).  My other option has been to wait till after he goes to bed, but by then I'm usually really tired.  My day starts at 3:30 am and I get home from work around 5pm.  I work 4 days a week.  I don't belong to a gym mainly because I can't fathom having my son in daycare for 11 hours, only to put him in another one for another hour or so, therefore I do it at home.  Any Moms or Dads out there that run into a similar problem?  I get my excercise in about 2-3 days a week now, mainly on my days off.  I husband and I are seperated, so I don't have any help at home.  I am aware that some of this is just excuses - that I have to just do it, regardless, but the mental part of things is tough.  Any help in that arena would be appreciated as well.

Thanks Neece - those are some great ideas.  I appreciate the help!!

Neece,  Normally, yes, the metro area does not get much snow, but the last 2 weeks in a row we've had blizzards, so currently we have lots of snow. ;-)   I will have to try the snow-shoeing.  Sounds like it would be fun.  Besides, if a 6 year old can do it, surely I can!!  lol ;-) Thanks for the idea - I really appreciate your input!!