Interestingly enough, there are
three big reasons people don't do things when they say they want to.
1. I don't think I can do this.
Especially if it's a big project or if it requires a certain skillset that you're uncertain of, it can be very easy to become overwhelmed. If the project is very large -- like major rebuilds of several large websites, which I started working on a year ago and got stalled until just now -- it's easy to have it loom so large that you don't even know where to begin.
Which means that it is first necessary to break it down into manageable pieces. That may mean subdividing a project into manageable units with clear milestones at which you can reward yourself. Or it may mean determining what skills or preliminary abilities you may need to develop before you can do the big thing. Running a marathon may not be doable if you've been a couch potato, but you can start by getting yourself up to running a mile.
2. People like me aren't good at this.
All of us develop an identity over the course of a lifetime, and part of it is based upon our membership in various groups. And sometimes the way our groups do things are contrary to the way the experts, or the crowd, are doing things. But it doesn't mean that you've got to force yourself to do it their way. Look for people who belong to your identity group and who are having success, and see how they go about doing the tasks you just can't tackle the standard way. Especially when it comes to human relationships, there are often multiple ways to accomplish the same thing.
3. I feel I have to do this thing, but I don't really want to.
The burden of Obligation is a very real thing. We know we ought to exercise and eat better. We know we ought to make a budget and get our spending back within our means so we can save money for emergencies. The list goes on and on, but everything on it has one common thread: it's there because someone else tells us we ought to do it.
Consciously or not, we resist being told what to do. We put up with it from certain people because they have something we want or they have the authority to make our lives miserable if we don't comply. But absent those things, we are apt to find excuses (and even when those circumstances are present, we tend to drag our heels until we can't avoid the problem any longer, viz. how many people are frantically trying to put together their taxes on the evening of April 15, every single year).
In order to get around this mental roadblock, we need to recast it as something we want for ourselves. Once our motivation becomes intrinsic rather than extrinsic, it becomes much easier to get the job done.