有始無終

to start but not finish (idiom); to fail to carry things through / lack of sticking power / short attention span

to have; there is / (bound form) having; with; -ful; -ed; -al (as in 有意[you3 yi4] intentional)

to begin / to start / then / only then

not to have / no / none / not / to lack / un- / -less

end / finish