<human>: Howdy all!

So, I'm on day two in a row of actually going to the gym (wahoo) although this may seem small, this is the start of me ACTUALLY working out.. or trying to.

My question about cardio is this:

So, when I'm tossin' bows on the fancy treadmill at my gym, it tells me lovely things like heart rate, distance, time, etc. One thing it tells me, of course, is calories burned (which I know is most likely estimated and what not) So, I've kinda set my goal per day as 2.5 miles, which I do at an average of 3.9mph (the fancy machine told me so). My question is, at the end of my workout it tells me I have burned around 155 calories. 

Now this information is disheartening, as you all know, everyone likes to focus on calories. So, should I be sad that I am only burning a measly 155 calories a workout, or is there some secret the fancy machine is keeping from me. (Like the concentration camp party it's throwing for my belly fat) OR.... am I walking 2.5 miles just for those 155 calories :/

Provide a brief overview of the text.
<bot>: Should I focus on calories burned during cardio, or smack myself in the face for being sad my workouts are burning only 155 calories (est.) a pop.