How initially 'to get her in the sack' and subsequently to avoid 'her giving you the sack' are not identical dilemmas faced by the male species, but they sure have a bizarre habit of being bedfellows
Never invest in any kind of relationship with anyone who is not willing to work on themselves just a little every day. A person who takes no interest in any form of self-improvement, personal development or spiritual growth will also not be inclined to make much of an effort building a truly meaningful connection with you. A relationship with only one partner willing to do the work ceases to be a relationship. And as anyone who has been there will tell you - it's pointless to try and dance the tango solo.