I used to do workout classes with my son when he was a year old. You can use him as extra weight. For example I would hold him against my chest as I did squats, sit him on my tummy as I did crunches, lay him on ly legs for leg lifts, lift him up into the air and lower him back own blowing raspberries as I did.
We would also set up a blanket and some toys, drink cup, snack cup etc so if he wants to wonder away from me he has something to do, eat and drink while I finish my workout.
Now that my son is 3.5 years old he knows to give me some space and time if I am working out at home. He will say to me "mama are you going to do your everyday crunch now?"
(I used to do Jillian Michaels 30 day Cruch DVD)
Also just some fun dance music and silly dancing for 30 mins is a pretty good workout and the kids love it!
Oh also I used to go on Urban hikes with my son in a wrap on my back, excellent resistance training as he was 30lbs by 1! I wish he would still let me wrap in but he will only let me for about 5 mins. Now we go for lots of walks as he rides his bike or scooter beside me.
I think it is really important for our children to see us being active people and to be active as a family. I am currently trying to implement family walks and hikes when my DH is home. That is another idea for you, to workout as a family.
Also don't beat yourself up if you can not get to or finish a workout as any amount of time you are active is a blessing to your health.