I’m struggling with excessive masturbation as well as a carelessness about myself resulting in actions that endanger myself as well as being dangerously overweight. I have tried to take control and regulate my habits but every now and then things happen and I’m back to square one.
I need to remind you again, this is a battle that you have to go through for life but (hopefully) it gets easier. This is the cross (there may be other aspects but for now this is what is what God is clearly focusing on) you carry (see Luke 9:23). When you sin (in this case, against your body), the bible tells you to go to God and seek forgiveness, go to the one you sin against and seek reconciliation.
The focus is not on how weak you are or how often you sin but how much you want to overcome and giving the Holy Spirit access to who you are. This is not about a single lift at the gym, but a daily exercise of your spiritual muscles, the condition of which you can clearly see.
You already have set goals to achieve daily and weekly to help you regulate yourself and exercise control. Begin each day with a sincere prayer of hope to overcome, seeking his grace; end the day with a sincere prayer of repentance and thanksgiving.
The devil will tell you that such a process is open to abuse but it demonstrates how much God trusts you to be sincere. He is not going to “zap” you and suddenly everything is cool or punish you until you behave (punishment is the way of the Law). He wants to train you to be an overcomer so hold on to hope and faith.