Bring the brown rice and water to a boil in a saucepan over high heat. Reduce heat to medium-low, cover and simmer until the rice is tender and the liquid has been absorbed, 45 to 50 minutes.
Boil, steam or microwave the pumpkin till cooked but not soft. When the rice has nearly finished cooking, heat oil in a frypan over medium-high heat and stir in the garlic and sage just until fragrant. Reduce heat to medium, stir in pumpkin and cook until it has bit of colour from frying, about 8 minutes. Stir in carrots and cook for 2 minutes. Stir in salt. Remove from heat; stir in the cooked rice until well blended. Serve warm.