Challenges?You might feel a bit sick for a few weeks. When I quit for 8 months in the Navy I timed it to coincide with already being sick so that I wouldn't notice it as much.
For at least 21 days you'll likely have strong cravings to smoke. It takes 21 days to create a new habit, so it's the same to break one. Commit to it. If you want to use the patch, use it strictly by the book. Don't cheat, or it's over. The gum, if it's available to you, isn't great in my opinion. Skip that one.
Commit to the idea that you're not a smoker. You sincerely have to convince yourself of your new lifestyle choice. Remember what it was like to be a non-smoker, and keep in mind all the great things happening as you continue not to smoke like easier breathing, more energy, and more money.