Exactly. Especially at first, you might want to build in some rest days. Let's say you wanted to do 20 min and the month is 30 days. 20X30 is 600 minutes, but if you miss even one day, you fall behind. You might want to, instead, think of 20 min 5 of 7 days... maybe that's 21 or 22 days total. A goal of 450 might be more reasonable to start.
I've been tracking minutes for about a year. I have never liked to exercise and found this was a great way to keep myself accountable. I commited
to doing my best to meet whatever goal I set, and haven't missed one yet (though I don't really go far over). I tried to set goals that are reasonable FOR ME each month. I've built endurance and ability over time, so my minutes have increased, but some months I have more time. If you look in my sig you'll see that when I had more time in the summer, I did more, but I cut back for my busy fall.
Did you know there's a forum on 3fc for people who start around or above 300 pounds? We're here:
We have this great exercise thread (stickied at the top of that page) where we not only set our own individual exercise minute goals, but also track group points! We are working on a goal of exercising 200,000 minutes this year!!!! I invite you to join us!