No, not push ups or sit ups.
And while we are not going to concern ourselves with lean muscle mass, I do want us to consider lean sentence structures. Too often, academics write sentences that are too long and too complex. Sentence which are too long are often confusing, hard to follow, and boring. They do not lead to greater understanding, but instead, obscure. Complex sentences should never be confused with important ideas.
Start with an article or something you are working on. Take a rough passage, perhaps a paragraph or two. When reading it through, consider sentence length. See if you can take what you have written and create some good lean, short sentences. Seek to reduce sentence length for the passage. Come back in a day or two, and read it again.