A really useful feature of Health Explorer in Operations Manager is the ability to force the agent recalculate health of a particular monitor. One the most common uses for this is when you want to confirm that the action that you took actually fixed the problem. If you have implemented your management pack correctly all you need to do is select the unit monitor in health explorer and click on the "Recalculate Health" button.
In order to make this button actually force your monitor to recalculate health state, you must do some extra work in your management pack, or else nothing will happen. This is especially important if you are either creating a new monitor type or creating a script based monitor. Basically when creating a new monitor type or creating a script based monitor, unless you do some extra work "Recalculate Health" will not do much for you and the users of your MP.