All of us have our good and bad 'faith' days. At times, our faith wanes and we feel tired doing even the most basic of religious duties, and at times, it soars to the Heavens, or higher, and we can't get enough of worshipping Allah.

Realize that the rise and fall of 'iman' is, in itself, something natural, and as long as we do not fall into committing majors sins or neglecting the obligatory deeds, there is no sin per se in merely *feeling* spiritually low. So, force yourself for the sake of Allah to do the obligations that are required of you, and slowly, your iman will continue to rise until you will cherish doing the excellence that is not required of you.