Imagine that it’s tea time and you’d like to eat a distant cookie. The speed at which you will walk toward this cookie will be modulated by your sensitivities to the energetic cost of movement (e.g., lazy vs. energetic), to the cost of time (e.g., patient vs. impatient), and to the reward (e.g., hungry vs. sated). How these sensitivities modulate behavior and their neural implementation remain poorly understood. Here, we tackled this question by combining experimental and theoretical approaches. We developed an automated foraging task in which rats have to run back and forth on a treadmill to get rewards. Within each session the probability of getting a reward was alternatively high (90%) and low (10%) in 5 min-long blocks. Across sessions, we manipulated the effort rats had to produce by either modifying the length of the treadmill while its speed remained null, or by manipulating the speed and direction of the treadmill to facilitate or counteract the animals' crossings. We quantified the number of crossings and the running speed. Rats did more crossings when the probability of getting the reward is high, confirming that they are reward and time sensitive (Shadmehr and Ahmed, 2020). Surprisingly, this effect was not paralleled by a modulation of their running speed which was identical in high and low reward blocks, suggesting that the animals display limited effort sensitivity. This asymmetric sensitivity for time and effort was confirmed when we manipulated the treadmill distance and its speed/direction. Interestingly, rats modulate their speed to maintain the same time delay between rewards. We are currently investigating the interindividual variability in effort/time tradeoff using optimal control theory and the potential contribution of the dorsal striatum in controlling this tradeoff.