If you have GAS, given your Sig, I would assume you have bought/sold a lot of lens.
Here's my (current) strategy for fighting GAS:
1. Come up with your basic kit requirements to limit the number/type of lens (mine is a kit of five L glass and two bodies).
2. Don't buy another lens until you have taken --- and post processed --- at least 1000 to 5000 shots per lens you already own.
3. If you don't use a lens or body enough in a six month to one year period, sell it (you will have to decide what level of usage this actually means).
4. Don't buy a very expensive lens until you have borrowed and used it at least twice, demonstrating in practice (not on paper) why you need it.
5. Invest in lighting instead of more glass. Master your lighting setup before buying more glass.
6. Supplement your lens collection by borrowing from your friends. (i.e., entice your friends to buy that great deal on a used 600L mk I so that you don't have to buy it and could just borrow it).