There were several different difficulties that settlers of Roanoke and Jamestown endured, including:
1) Hunger- One of the biggest struggles faced by the first English colonizers was hunger. This was a factor because the members of these new colonies were unfamiliar with the growing season/climate of the territory where they lived. This resulted in very little agricultural success.
2) Disease- The first settlers of these colonies encountered diseases they were not immune to. Along with this, they encountered diseases through poor sanitary practices (like drinking dirty water).