My attention span can be a real problem, if I constantly check things online throughout the day then I can't do anything meaningful in terms of work because my attention just cannot focus.
I have at times in the past stop reading things online and on my phone completely for weeks and its amazing how much more productive you become. For some reason though I can never keep it up and the interweb drags me back into procastination eventually.
I think people dont realise what a detrimental affect it has on them until they give it up, I didnt either until I gave it up for lent one year and suddenly I found myself far less irritable, I was sleeping better, and overall felt better.
I dont think multi-tasking is the solution to lack of attention span at all, it may help in the short run but is actually the opposite of what you should be doing to address the problem. You need to get used to focusing on one task and in the start it pretty much means forcing yourself to do just one task, even if focusing on it is a real struggle.