Set some goals.
It's hard to get back into the swing of things without something concrete to work for. Sit down and plan out some goals that you would like to achieve, that all build into each other.
As Sean points out, it does come back quickly. At 5 weeks, you are not completely detrained yet. Common lore is that depending on your own personal physiology, you can get away with a week or two of inactivity. After that time, you lose about 2 days of fitness for every day of continued inactivity. So it will take you a couple months to get back to about where you were before the off time.
Also, don't beat yourself up about it. Life happens to everyone. Unless fitness is your monetary occupation, it's ok to wander off into the weeds now and again. Set some small goals, such as "Get into the gym 2 times this week, and 3 times next week". Once you get those, then plan some bigger goals. You should always have some short term, medium and long range goals that you are working towards.