The "I19 Mids" that's floating around out on the forums is an unofficial database edit, not done by the Mids team. Mids will be out within a few days. In the meantime, you can do the following to simulate I19 numbers:
1. Open Mids. This will be called Mids1.
2. Open Mids again. There should be two Mids windows now. This will be called Mids2.
3a. In Mids1, build your character as if it has inherent fitness.
3b. In Mids1, place empty slots somewhere (rest and sprint are the most common suggestions) as if they were going into your inherent fitness, but do not place anything in them.
3c. In Mids1, check your totals.
4a. In Mids2, select ONLY Fitness Pool -- do not take any other primary/secondary/pool powers that will alter anything that fitness pertains to; +HP, regen, +end, recovery, run/jump/fly speed/height, mez resistance.
4b. In Mids2, place slots as preferred in Fitness Pool, slot nothing anywhere else.
4c. In Mids1, add your Mids2 Fitness-modified totals to 3c.
Complicated, sure. If you don't care about what your totals are with/without fitness, as long as you've got slot allocation done, you can instead only do Steps 1, 3a, and 3b. This will leave you with less regen/etc. than if you had inherent fitness with slots, but at least you've got everything else.