One reason why so many people probably fail at IM is because they just don't have time.  You probably have a job; you may have a significant other or spouse, kids, pets, friends, etc...
There is only one of you.  There are only so many hours in a day.   You have to decide how to allocate yourself to everyone and everything in your life.

This includes your Internet Marketing (IM) activities. If you have the greatest software or IM strategies in the world you may still not be successful.  If the strategies or software are
complex, which in turn would make them time consuming, you may get frustrated or distracted and give up. 

The best tools in IM are the ones that are neither complex nor time consuming.  It also helps if they are more than theory and have proven results.

What are your biggest and most time consuming IM stumbling blocks?
Finding a niche?
Keyword research?
Writing content?
Finding affiliate products to promote?
Making a header?
Making an eye catching site?
Putting a name and email capture box on the page?
Writing an autoresponder series?
Writing product reviews?
Figuring out how to get traffic?

If you're like most people who do IM at least one of the above, if not more, are one of the reasons that makes you feel like you're being held back and why you're not successful.

The best way to overcome some of these obstacles is to build a solid foundation of knowledge in most if not all of these areas so that you spend less time wondering what to do and more of your available time actually doing what will make you successful.

If you are not sure how to go about getting that solid foundation, let me suggest you start with a free membership at a site like Affiliate-Blaster.com  -- where you will have access to the basic information and training you need to know to build your business.