Z powodu braku rzeczywistego kontekstu podaję dosłowne tłumaczenie - jednak właściwszym określeniem może być: ponadstandardowy wkład pracy.

Nagroda lub wynagrodzenie musi – stosownie do oczekiwań pracownika – uzasadniać dodatkowy wysiłek, niezbędny do zwiększenia własnej aktywności i efektywności oraz bezpośrednio kojarzyć się z jej wzrostem.
http://praca.gratka.pl/tresc/art/czy-poczucie-sprawiedliwosc...

This additional contribution or effort that employers are seeking is called ‘discretionary effort’ and involves seeking, acknowledging and reinforcing the behaviours that add the ‘x’ factor to any performance.
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Discretionary effort - what is it? How does an organisation capture it? What do we need to do to entice individuals to trade their extra energy and time for the organisation? Discretionary effort is the difference between how well people actually perform and how well they are capable of performing.
Discretionary effort could represent a range of performance as broad as 20% to 40% above the performance actually realised by an organisation and could be directed toward improved output, results, quality, customer service, and safety.
http://www.buckettlaw.co.nz/SITE_Default/fyi/trends_library/...

There is a concept called discretionary energy or discretionary effort. This is the effort / energy that an employee chooses to exert in service to coworkers or customers at work - or not. An employer pays for the fundamental tasks that he hires an employee to perform. The employee's willingness to perform above and beyond the basic requirements of the job is a reflection of the employee's willingness to engage his or her discretionary effort / energy.

From an employer's point of view, the more employee discretionary effort or energy that you can tap, the better your potential for well-served customers.
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Won't you take the time to share an example of a time when you, a coworker, or a reporting staff person went the extra mile and tapped into their discretionary effort to accomplish an objective at work.
http://humanresources.about.com/b/2010/05/23/tap-into-discre...