Bitterness and resentment, whether they be towards God or towards others, will definitely destroy your testimony. They will steal your joy and destroy your relationships. Here are some quick links to blogs that address this topic.
In general:
https://perfectjoyministries.wordpress.com/2012/11/01/resentment/
https://perfectjoyministries.wordpress.com/2013/02/28/allow-the-redemption/
https://perfectjoyministries.wordpress.com/2013/04/15/the-double-edged-sword/
From the past:
https://perfectjoyministries.wordpress.com/2013/03/21/filters-from-the-past/
https://perfectjoyministries.wordpress.com/2013/06/26/changing-the-filters/
From unfulfilled desires:
https://perfectjoyministries.wordpress.com/2013/05/23/that-was-it/
https://perfectjoyministries.wordpress.com/2013/08/21/painfully-un-pregnant/
https://perfectjoyministries.wordpress.com/2013/01/13/dear-god-fix-this/
https://perfectjoyministries.wordpress.com/2014/07/03/consuming-desires/
Towards other people:
https://perfectjoyministries.wordpress.com/2013/03/07/when-people-arent-god-is/
https://perfectjoyministries.wordpress.com/2012/12/13/fielding-the-comments/
https://perfectjoyministries.wordpress.com/2013/04/10/present-filters/
https://perfectjoyministries.wordpress.com/2013/04/17/filters-from-the-future/
https://perfectjoyministries.wordpress.com/2013/07/07/limited-attention-span/
https://perfectjoyministries.wordpress.com/2014/02/06/who-says/
In marriage:
https://perfectjoyministries.wordpress.com/2012/12/20/keeping-your-marriage-intact-part-i/
https://perfectjoyministries.wordpress.com/2012/12/27/keeping-your-marriage-intact-part-ii/
