How can you measure your level of intensity during a physical activity? .

Taking your heart rate or pulse before, during and after physical activity 

Nothing will delay it, but drinking some lemon (squeeze 3) would cut it, making it last a few days, but its not good to do that. won't hurt you but the next month will be more cramps.. take some advils with you on the trip

Answergoing for a brief walk ahead of time and stretching afterward;