I get more motivated to exercise at home by myself than going out, or meeting someone to walk or something. I know if I joined a gym or hired a personal trainer I wouldn't stick to it, especially this time of year when it's SO cold outside and I'm just not going to get up early when I'm tired, it's cold and dark outside to work out (I'd have to go before hubbie has to go to work). And I'm not going to leave the house when he gets home from work either. So I have to work around this.
I use exercise videos - I've had good success with TaeBo and Cathe Frederich's Kick, Punch and Crunch. I also run on the treadmill. Then I lift weights too and do resistance exercises. I have a modest dumbbell collection at home - 3, 5, 10 lbs and a 5 lb weight disk, as well as a stability ball. I find I can do most exercises with these.
I also bought Women's Health Big Book of Exercises. This has taught me how to lift the weights properly and which muscles I'm targeting. HUGE help. I use this book almost every day. I highly recommend it for you if you want to build muscle.
http://www.amazon.com/Womens-Health-Big-Book-Exercises/dp...
Right now my routine is running on the treadmill and lifting weights (as well as watching what I eat, of course) and I'm starting to see results, so that's keeping me motivated. I'm at it about 45 min a day from shoes on to shoes off.
If I run on the treadmill, I let my son (who is 3) pick his fav cartoon and that gives me just the time I need. If I'm doing a video I'll encourage him to join me and make it fun that way - but usually he just watches me (although he doesn't laugh at me flailing round *yet* so it's all good :). He'll watch me do weights to (I'll have him count out my repititions), but usually he wants to play with the weights so he can do what I do, which can be a problem, so I'll get out some toys for him to play with.
Good luck!