One week in and today's challenge is going to be as much a mental challenge as it is physical. So spend some time getting your head in the game before you begin.
Hold forearm plank for time.
Rest 90 sec.
Hold tall plank, for time.
Revisit Day 1 and Day 2 to remind yourselves of the basics.
Focus on quality over time even though today's challenge is for max times.
Know what your previous best times are for each of these. There will be mental battles before today's challenge ends and knowing your target times while in the plank will help you stay in it when your minds telling your body it's time to quit.
When you are at your limit, you should remind yourself that it's going to take all this time again the next attempt, just to get to this testing point. So don't waste this opportunity and 20 sec after you stop, and the pain fades, regret that you didn't fight for a little longer.
Quality or nothing! The time is meaningless if it's not a quality hold.