You push your body to it's limits very often when your adrenaline gets going, and that gives you a major advantage in certain situation, but at the cost of harming your own body in the  process, and in turn your body has grown accustomed to your habits and thus adjusted accordingly.
You gain the following effects:

• Your maximum exhaustion level is increased by three, where as the first three levels don't affect you, then from the 4th, the effects of exhaustion are normal (Disadvantage on ability checks starts on 4th level of exhaustion, and 9th would be death.) And instead of one exhaustion level being removed per long rest, two are removed instead.
  
  
• When you dash or jump, you could further increase the dashing/jumping distance by half, at the cost of gaining one point of fatigue. You can only use this once per dash/jump.
  
  
• When you make either an attack roll, acrobatics check, athletics check, CON check. CON saving throw, STR saving throw, you can choose to gain one exhaustion level and add +1 to the roll, and before the outcome of the roll is decided, you can choose to add more than a single point and gain one exhaustion level as many times as you choose, as long as you don't have 8 exhaustion levels or more after using this effect.
  
  
• You can choose to gain one level of exhaustion to add a +1 to any exhaustion related roll before knowing the outcome (Including making a saving throw related to Sickening Radiance or such), if you succeed, you don't gain any exhaustion levels from what you would have gained from adding to that roll. If you fail that roll, you still add the exhaustion levels. You can add only up to a maximum of +3 this way as long as the exhaustion wouldn't reach the 8th level from this effect. You can't use this effect on rolls related to not getting long rests, not drinking water and not eating.
  
  
• Once per three days, when your hit points drops to 0, you can choose to gain five levels of exhaustion, and in return you regain Hit points equal to your level +CON modifier. Until the end of your next two turns, you don't have any disadvantages related to your levels of exhaustion, (Or somewhere ranging around 30 seconds.), and any damage that you would take would be reduced to 1, and at the end of those two turns, you become unconscious and can't regain consciousness unless at least five levels of exhaustion are removed, either by being unconscious for three days (Each day will equate one long rest.), or by a spell or other effect that removes exhaustion levels, or a combination of both as long as five levels of exhaustion are removed. You can't use this effect if this effect would put you at 8 levels of exhaustion or more.
  
  
• When you attempt to lift a creature or object, you can choose to gain one level of exhaustion in exchange for adding a d20(lbs) to your carry capacity. This effect lasts for five minutes, and after that, your carry capacity will return to normal. You can only use this effect up to three times at the same time, and any additional time you use it before the time of this effect ends will not increase the remaining amount of time that remains for this effect.