有始無終

有始无终
yǒushǐwúzhōng
  1. to start but not finish (idiom); to fail to carry things through
  2. lack of sticking power
  3. short attention span

CEDICT

  1. to have a beginning but not an end
  2. to start something but fail to carry it through; to begin well but end badly

Wiktionary

有開頭而無結尾。比喻做事不能貫徹到底，半途而廢。

重編國語辭典

Entry Composition

1 有 yǒu
  1. to have; there is
  2. (bound form) having; with; -ful; -ed; -al (as in 有意 yǒuyì intentional)
2 始 shǐ
  1. to begin
  2. to start
  3. then
  4. only then
3 無 wú
  1. not to have
  2. no
  3. none
  4. not
  5. to lack
  6. un-
  7. -less
4 終 zhōng
  1. end
  2. finish

Related entries

為德不卒 wéidébùzú
  1. to start on virtue but give up (idiom); to fail to carry things through
  2. lack of sticking power
  3. short attention span
為德不終 wéidébùzhōng
  1. to start on virtue but give up (idiom); to fail to carry things through
  2. lack of sticking power
  3. short attention span
一曝十寒 yīpùshíhán
  1. one day's sun, ten days' frost (idiom, from Mencius); fig. to work for a bit then skimp
  2. sporadic effort
  3. lack of sticking power
  4. short attention span