It is hard - because its an addiction. Its just as hard as a smoker trying to quit smoking.
You will only stick to your diet and be successful when you psych yourself into it enough.
By telling yourself you can't eat certain foods, it makes them all the more appealing - and in the end, you cave in and eat a triple helping (its what I did!)
Maybe to help fight some cravings - tell yourself, will this really taste as good as how good I will feel when I reach my goal weight.
SO what you should do, for the first little bit while you gently ease yourself into your new routines - is eat when your hungry, don't try to fight through hunger pains. For starters, eat healthier alternatives of the food you are already eating (for example, if you like eating pizza - make it homemade! A wholemeal pizza base, lots of veges and some mozarella, mozarella is actually healthy in reasonable portions) Cut out sodas and sugary juices and try to stick to water - you will cut out a lot of calories by purely doing this.
Once you get that under control, you can slowly get more harsh on your food choices and portion sizing.
Most important - if you slip up once, don't tell yourself "oh well, todays ruined so I may as well eat whatever I want and start again tomorrow". Just continue the diet that day - or you just consume a lot of extra calories that could have been avoided.
As for exercise - buy a skipping rope. No excuses - because you can do it at home, you can do it infront of the tv. Personally, I bought one because I am quite a home body! So I made a rule for myself - every ad break I had to get up and jump rope till the show was back on.
3months ago, I was 210lbs. Now I am 170lbs. Its working for me :)