I've tried to try. I've reached the end of my wits in figuring out ways to try in chess. For every one game in which I do try, there are about three in which a slip-up due to laziness in a critical moment spoils all the excellent play up to that point (or it may kill a potentially good game before it can get started, both are just as emotionally painful). Below is an example of the former

The type of game like the above happens to me much of the time. I make a great move (9...cxd4 and the tactic that followed) and later a colossal blunder (34...Rb6, I don't even want to talk about it). I've stopped trying to make sense of this madness and have decided that I need a little bit of help to break free from this spell of laziness. Short of Ritalin, does anybody have any such a solution to the problem, or am I just screwed for life?

I found in OTB games that every time I made a move quickly without fully checking my opponent's responses, it would be a terrible blunder.  I was also very disgusted, and became paranoid about making a quick move.  Now I have the problem of taking too much time... but at least my mistakes are honest "I couldn't find the reason why not" mistakes instead of "I was too lazy" mistakes (not that I never make simple oversights...)

The "cure" is to form good habits.  Once you decide on a move, visualize it as if it's been made and switch all your thinking to your opponent's pieces.  Check everywhere they can move, check, and capture you.  Usually you look at the options for your pieces only and only look at enemy moves as responses.  This is not the way to do a final check.  The final check involves only looking at your opponent's pieces (for every check, capture, etc).  If you only do this 9 out of 10 moves like you've seen it's not enough.  And once you make it a habit it becomes easier.

Whenever I'm disgusted at losing a game, or a terrible mistake, I remember every player has to struggle with these things.  Everyone has shameful losses to weaker players after 40+ excellent moves only to lose on the 41st -- that includes Grandmasters and world champions too.  So take heart, you're in good company :) and try to work on better habits during future games.

Blunders are very common to every one below 1800 rating. In fact some one in an article suggested that at 800 almost every move is blunder(16 in a game), at 1200 it drops to 4 per game, at 1600 it drops to 1 in a game. After that at 2000 blunders occure once in 4 games, at 2400 rating once in 16 games. So you are very close to eliminating them !!