Running an Executable (Should be Easy, Right?)

Remember in Windows when you move to a directory like this?
cd dir1
cd subdir2

And then you want to run an executable file in subdir2?
exec1.exe

All good? Try that in Linux, and it is always trying to load the file from the /usr/bin folder. If you actually want to tell Linux to load from the folder you have just spent 15 minutes navigating to, type;
./exec1

The joys.