I have a lot of irons in the fire. I have no problem getting started, its finishing before i'm off to something else. Also, more insidiously, this seems to have infected everything in my life. Work, cleaning the house, exercise, reading, writing, gaming, etc.. ITs like ive lost a balance and cant right the ship.
This sounds a lot like one of the more common experiences resulting from the pandemic.
Some partial solutions for you may sit in time management techniques. I, and probably several others, can show you a few of those, I expect.
But, for many that's treating a symptom, not the root problem - the pandemic, overall, in its many facets, counts as trauma, and for many, what you are speaking of is a set of common trauma responses. The best way I know of to handle that is to speak with a therapist.