77 Branches of Imaan
RasululLah SAW said there are over 70 things which are connected with Imaan, the highest of which is the Kalimah Shahadah and the lowest is the removal of a harmful object from the road. Modesty and hayaa is also a major part of Imaan.
Imaan means to accept in your heart (Tasdiq Bil Qalb) and bear witness verbally (Iqrarun Bil Lisaan).
When you scan through the list and read the commentaries, you will realise that Islam is indeed syumul (complete). Every good deed, even one which is 'as small as an atom' gets rewarded by Allah SWT by elevating one's Imaan to a higher point, Subhan Allah.
If you are keen to know the details, with ayat and hadeeth cited, download the book Furu' ul Imaan.