Your problem is lack of confidence.
Lack of sleep had made him irritable.
If he fails it won't be through lack of effort.
She certainly has no lack of friends.
a lack of money
If you like nature, wish to see tropical birds, which are rare in your country, or just wish to have a pleasant time, the countryside is the best option, [despite] the lack of nightlife. (Preliminary English Test; B1; Portuguese)
She just lacks a little confidence.
He’s totally lacking a sense of humor.
What we lack in this house is space to store things.
He lacks confidence due to such a terrible appearance. (First Certificate in English; B2; Korean)
He's totally lacking in charm of any sort.
On the other hand, Japanese children are lacking in creativity and originality. (Certificate in Advanced English; C1; Japanese)
Enthusiasm has been sadly lacking these past few months at work.
And, last not least, I would really like to show them the importance and beauty of our cultural heritage which was lacking in my upbringing. (Certificate of Proficiency in English; C2; German)
