Usually it is the problem of not knowing the immediate next step and not debugging past fiasco incidents thoroughly enough.

Such incidents (not mailing the important letter for 4 days, with a USPS box a minute away) need to go through a post mortem analysis: why did it take 4 days? Is it because cryingontheinside had no stamps? Or were the stamps too old - insufficient postage? Or was the subject matter of the letter emotionally charged, causing procrastination and avoidance? Out of ink? Need to find the addressee's full contact info? Did not know what to write? Was the letter free text or did cryingontheinside need to fill out a form, and in the latter case, was it clear how to fill out the form or were there lengthy instructions that were a prime reason to procrastinate? Was there resistance to success lurking in the back of the mind? (If I send the letter on time, I will achieve ABC, and since I do not feel worthy of anything positive, I will sabotage writing that letter).

And many other questions that can be pondered.

Feeling aggravated or berating yourself or feeling annoyed with yourself is all not just useless, but counterproductive, because just as success breeds success, so, too, failure breeds failure. A person who thinks of oneself as a procrastinator is not going to attack a problem with vigor, right?

The only helpful approach is figuring out why things do not get done and frequently asking yourself the question: "What is my next step? Do I have everything I need?"

To send a letter, you need paper and pen / printer, an envelope, enough postage, the addressee's contact info, and possibly a lot of info that is scattered around in different places just to put together the text. It is not a trivial matter - the level of complexity is fairly high. To take out the trash, you need sheer will power or a way to look at taking out the trash as a welcome change from whatever you have been doing on the computer; this is because taking out the trash is trivial. Sending an important letter is not trivial.