We often have to make decisions based on what our future selves are going to do. When we make those kinds of decisions we need to be careful to predict our future selves as what they will be not what we want them to be.
People sometimes have unrealistic fantasies about who they're going to be in the future. They think that by some time, they will have gotten their act together. When they have these idealistic depictions of their future selves, they make decisions that their future selves won't be able to deal with.
The college drop out rate is depressingly high. A lot of those students would have been better off if they had never gone in the first place (and consulted Bryan Caplan's blog post before making that decision). So what happened? Well, these students usually didn't do well in high school, which should have been evidence that college might not be the right decision. Instead of following the evidence they convinced themselves that they're going to get their act together, do their homework, listen to their teachers, and graduate college. So they made all sorts of investments in time and money based on that unrealistic depiction of their future selves, and dropped out without a thing to show for it.
We make the same mistake for shorter time horizons too. Downloading habit bull is a waste of your time if your future self can't be trusted to use it.
And oh my god stop buying workout devices, machines, tapes, and all the rest (unless it's IronGym). They're not worth the price, not to mention the clutter! Musical instruments work the same way; how about learn how to play before you buy.
It all comes down to seeing your future self from the outside view rather than the inside view. What will your future self be like? Start by taking a fair look at your present self.