Inconsistently Consistent

Or am I consistently inconsistent? One of the two. I always have these grand schemes for life improvement, but I have so much trouble creating consistent habits. Exercise, for one thing. I will get into a habit for weeks on end and be very consistent, but then get out of the habit again, on and off in a cycle. Same thing with eating healthy, keeping the house clean, setting out outifts the night before, getting library books back on time, making time for spiritual reading, making and implementing structured meal plans, putting things away after I use them, turning off lights, limiting extra spending. I get so frustrated with myself! Part of the problem is that I always want to completely improve every area that is lacking in my life all at once. I think I need to choose one thing a month and slowly snowball them all in over a year's time. I just don't have the patience for that! I know it takes something like 21 days to make a habit though. How can I pick which one is most important to start with? How about healthy eating, like cutting down on simple carbs and sugar and replacing with complex carbs paired w/ protein. Next week I need to stop taking Metformin for insulin resistance since I'll be 11 weeks pregnant, so that seems pretty important to my health. I'll let you know how it's going next month. :)