It depends on how quickly the war ends
Let's take this track
Britain comes to peace with Germany after 1940 (forget why it doesn't matter)
The Soviet Union ass womps finland enough to convince Hitler they aren't an easy target
The Soviet Union allows German spies to see exactly how big their tank and aircraft park is
Hitler postpones barbarossa for a good while
In 1939-barbarossa, Hitler was under a decent amount of stress, however his sleeping and eating habits where not totally unmanageable, and he was having much shorter bursts of action and excitement and hard decisions as opposed to a daily ordeal (ie the polish campaign and the campaign against france where pretty short)
If you close the war prior to barbarossa, there is a good chance his stress levels go down; perhaps he takes some several weeks of vacation with Eva to decompress which gives him a chance to break his work cycles
If this period of not shooting at anyone holds and Hitler becomes convinced that he has gone as far as he can go (probably asb) its possible Germany could spool down their war economy so that they can start to function semi normally again,
Also since this is pre barbarossa, he hasn't fired the army high command yet, so he is just head of state with one set of responsibilities, not burning himself out playing field marshal as well
Under this circumstance, he could probably live until at least 1950, if not a bit later... he didn't smoke or drink and he went for long walks pretty often