"Do not lay up for yourselves treasures on earth, where moth and rust destroy and where thieves break in and steal, but lay up for yourselves treasures in heaven," -Matthew 6:19-20 (ESV)
Say you're living in an incredibly small apartment. The walls are somewhere in-between pink and beige, the floors, bright orange shag carpet, and stained with who knows what. The shower is about a 2x2 foot space, and the fridge can hold a quart of milk and maybe a couple cans of soda, and your stove, well, you don't have a stove. How excited are you about living here? I don't know about you, but I wouldn't want to live there at all. So you have a choice. You just graduated college (look at you go!) and you have a job, but not a whole lot of money. So you have two choices: You can invest time and money into fixing the place (assuming the owner of the complex doesn't mind), or you can save that money and use it to buy a house later, that has nice carpet and a stove, and can fit more than one or two people in it at a time. Which would be the wiser choice? Well, fixing up the apartment would be easier, but ultimately, you would end up benefiting more from saving up the money to buy a new house. Right?
Our lives here on earth are much like that itty bitty, horrifyingly small apartment. Sometimes, we get side-tracked. We forget that we are ultimately striving towards a higher goal than just making our "apartments" better. Whenever we sin, we are investing in our lives here on earth. We are attempting to make it cozier for us now, rather than later when we realize that we could be in heaven, but we spent so much time and money building up our earthly lives, that we have forgotten what is really important. No, there is nothing wrong with having a job, and trying your best in school, and making friends, etc. In fact, those are all really good things. But it's when you make those the things that you strive for in life, and put them equal to, or above God, that it becomes a sin. It's when you lie to get that promotion, or stop going to worship so that you can have more time to study. It's when you stop evangelizing because you're afraid your friends will leave you if you talk about the Bible. That's when you stop making the best of this life, and start investing in it.
So how do you stop investing time in this life, and start investing it into the next? The best way to start investing in God, is to stop investing in yourself. Stop making excuses for why you can't study your Bible, or why you can't share God's Word. Take time out of every day, and dedicate it to God. Take an hour or two out of your daily schedule, and use it to serve God, and only Him. Lay up your treasures in Heaven, not here on earth. You might be surprised how much easier it gets living here, when you remember that one day you'll be in heaven, and none of this will matter anymore.