I propose to fight it out on this line, if it takes all summer.

Choosing a line and staying on it is worth more than choosing a clever one. Most plans fail not because they were wrong but because the person switched approaches the moment progress slowed, and each switch throws away everything the previous attempt had built. Deciding in advance that it will take as long as it takes removes the daily question of whether to keep going. The commitment is to the duration, not just the direction.

Pick the one effort that matters most and set a horizon you will not renegotiate before, in weeks rather than days. When it gets slow, treat slowness as expected rather than as information.