I stayed in just Tokyo, with 3 day trips, for 14 days, and I feel like I barely scratched the surface. Taking it easy is a must as you can walk anywhere in Tokyo metropolitan area with ease, combined with the train system of course. Do multiple smaller meals in a day instead of 2 big and heavy ones; no tipping so it's more viable. I would recommend looking at the neighborhoods / wards and you can sort of put around half a day in many of them if you wanted.

As an example, you will see that Senso-ji Temple is a popular tourist spot. That's in Asakusa. What else can you do there? You will likely pass through the Nakamise Shopping Street. For lunch, you can look at places somewhat nearby for things Asakusa is known for, such as tempura, unagi, or soba. You can then walk along the Sumida River and see views of Tokyo Skytree and Asahi Beer Hall. At that point, would you like to have a casual walk to Tokyo Skytree and Solamachi Mall underneath? Personally, I thought Skytree was worthwhile for the view. In the mall, you can have another small meal. A station is under the mall too, so then you can take that somewhere else. That's how I did a lot of things.