Preheat your oven to 400°F and line a large sheet pan with parchment paper.
Peel the sweet potato and cut it into 1/2-inch cubes.
In a small bowl, whisk together the olive oil, minced garlic, rosemary, thyme, salt, and pepper.
Toss the sweet potato cubes with one-third of the herb oil mixture and spread them out on the prepared baking sheet.
Roast the sweet potatoes for 15 minutes.
While the potatoes roast, trim the woody ends off the asparagus and rub the chicken breast with half of the remaining herb oil.
Move the potatoes to one side of the pan, then add the chicken and the asparagus to the other side.
Drizzle the remaining herb oil over the asparagus and toss to coat.
Return the pan to the oven and roast for an additional 15 to 20 minutes, or until the chicken reaches an internal temperature of 165°F.
Remove from the oven and drizzle the lemon juice over the chicken and asparagus before serving.