One of the biggest reasons people stop exercising is not seeing results. Especially early on in our training I encourage my clients to notice all the small changes in not just how their body looks but how it functions! Sometimes we're so outward focused we forget to recognize how quickly we suddenly got up from the floor, how picking up and holding our child was so much easier than last time, how mowing was no longer a strenuous workout!
Here's a great article from Livestrong.com describing the results you can expect to see at 1-3 weeks, 4-6 weeks, 7-12 weeks, 12-24 weeks and beyond. How Fast Will Exercise Change My Body?