The first dollar is usually the hardest though. This is a true account of one person's experience and I think a lot of people don't understand what that feels like. 200+ hours to cheer for $1 and some people don't even get to the dollar.
The first $1 is easy.... If you're struggling to attract a single customer you seriously need to re-evaluate what you're doing. As mentioned earlier in the comments; doubling from MRR from $40,000 to $80,000 is a way bigger challenge than making that first buck.