Whats the hardest job when you are restoring a car

i would have to say planning the build. When i took my truck apart i was just gonna rebuild the motor. After i put a little cam in it, i kinda wish i would have built a stroker motor. interior is all out gonna put in bucket seats. and i want to build it a wood bed because i think a d150 with a wood bed and big tires up under the rear end would look good. it's really hard to plan them and stick to your original plan