It's definitely not silly! I normally find it easier to build up my exercise once I've got into a routine with one thing at a time. If I try and do too much at once I inevitably give up all of them after a little while. So this time around I am aiming for 30 mins a day, and one Zumba class a week until I get into routine with that, then I will join the gym and add a couple of sessions there, then add in some swimming once I'm used to that!
Also, since it's a very realistic goal - you'll be much more likely to accomplish it and then you get the little buzz of knowing you achieved your first goal!