How do I take my foot off the gas? (AN1)

Definitely not planning to stay in IB past 2 years and bonus band at my firm is ~15k; even bottom bucket got paid very well this year. My question is twofold then:

1. If promotion and compensation incentives are out the window for me - is there anything to lose from trying less at my IB job and dedicating my time elsewhere? It seems, logically, that it makes the most sense to try less at this job and focus more on prepping for my future job; I mean how much of the head-down PPT execution work is really going to transfer beyond my analyst stint? (e.g. rather than being ultra-responsive or being able to build a flawless deck in PPT, spending my time doing PE modeling prep or reading about companies / thinking big picture)

2. Most critically - how does one do this? I find it extremely difficult, although I accept this mode of thinking, to act on it. I find it impossible to not care or give less than 100% on the tasks I am given, even knowing that all that extra effort is really for - at least on the surface - is a few extra k's on my bonus. How do I not care - so I can not only live more comfortably at work, but use the time to my advantage?